Everything I know about good API design

https://www.seangoedecke.com/good-api-design/

by ahamez • 11 months ago

429 160 11 months ago

seangoedecke.com

cyberax6• 11 months ago

You should let people use your APIs with a long-lived API key.

Sigh... I wish this were not true. It's a shame that no alternatives have emerged so far.

TrueDuality4• 11 months ago

There are other options that allow long-lived access with naturally rotating keys without OAuth and only a tiny amount of complexity increase that can be managed by a bash script. The refresh token/bearer token combo is pretty powerful and has MUCH stronger security properties than a bare API key.

rahkiin2• 11 months ago

If api keys do not need to ve stateless, every api key can become a refresh token with a full permission and validity lookup.

maxwellg• 11 months ago

Refresh tokens are only really required if a client is accessing an API on behalf of a user. The refresh token tracks the specific user grant, and there needs to be one refresh token per user of the client.

If a client is accessing an API on behalf of itself (which is a more natural fit for an API Key replacement) then we can use client_credentials with either client secret authentication or JWT bearer authentication instead.

0x1ceb00da2• 11 months ago

The refresh token/bearer token combo is pretty powerful and has MUCH stronger security properties than a bare API key

I never understood why.

pixelatedindex4• 11 months ago

To add on, are they talking about access tokens or refresh tokens? It can’t be just one token, because then when it expires you have to update it manually from a portal or go through the same auth process, neither of which is good.

And what time frame is “long-lived”? IME access tokens almost always have a lifetime of one week and refresh tokens anywhere from 6 months to a year.

rahkiin2• 11 months ago

Inthink they are talking about refresh token or Api Keys like PATs. Some value you pass in a header and it just works. No token flow. And the key is valid for months and can be revoked

cyberax6• 11 months ago

If you're using APIs from third parties, the most typical authentication method is a static key that you stick in the "Authorization" HTTP header.

OAuth flows are not at all common for server-to-server communications.

In my perfect world, I would replace API keys with certificates and use mutual TLS for authentication.

smj-edison• 11 months ago

Every integration with your API begins life as a simple script, and using an API key is the easiest way to get a simple script working. You want to make it as easy as possible for engineers to get started.
...You’re building it for a very wide cross-section of people, many of whom are not comfortable writing or reading code. If your API requires users to do anything difficult - like performing an OAuth handshake - many of those users will struggle.

Sounds like they're talking about onboarding specifically. I actually really like this idea, because I've certainly had my fair share of difficulty just trying to get the dang thing to work.

Security wise perhaps not the best, but mitigations like staging only or rate limiting seem sufficient to me.

xtacy• 11 months ago

Are there good public examples of well designed APIs that have stood the test of time?

binaryturtle• 11 months ago

I always thought the Amiga APIs with the tag lists were cool. You easily could extend the API/ABI w/o breaking anything at the binary level (assuming you made the calls accept tag lists as parameters to begin with, of course).

pixl974• 11 months ago

While the author doesn't seem to like version based APIs very much, I always recommend baking them in from the very start of your application.

You cannot predict the future and chances are there will be some breaking change forced upon you by someone or something out of your control.

claw-el3• 11 months ago

If there is a breaking change forced upon in the future, can’t we use a different name for the function?

soulofmischief• 11 months ago

A versioned API allows for you to ensure a given version has one way to do things and not 5, 4 of which are no longer supported but can't be removed. You can drop old weight without messing up legacy systems.

CharlesW• 11 months ago

You could, but it just radically increases complexity in comparison to "version" knob in a URI, media type, or header.

Bjartr• 11 months ago

See the many "Ex" variations of many functions in the Win32 API for examples of exactly that!

jahewson• 11 months ago

/api/postsFinalFinalV2Copy1-2025(1)ExtraFixed

pixl974• 11 months ago

Discoverability.

/v1/downloadFile

/v2/downloadFile

Is much easier to check for a v3 then

/api/downloadFile

/api/downloadFileOver2gb

/api/downloadSignedFile

Etc. Etc.

ks20482• 11 months ago

If you only break one or two functions, it seems ok. But, some change in a core data type could break everything, so adding a prefix "/v2/" would probably be cleaner.

andix3• 11 months ago

I don't see any harm in adding versioning later. Let's say your api is /api/posts, then the next version is simply /api/v2/posts.

choult• 11 months ago

It's a problem downstream. Integrators weren't forced to include a version number for v1, so the rework overhead to use v2 will be higher than if it was present in your scheme to begin.

paulhodge• 11 months ago

I have to agree with the author about not adding "v1" since it's rarely useful.

What actually happens as the API grows-

First, the team extends the existing endpoints as much as possible, adding new fields/options without breaking compatibility.

Then, once they need to have backwards-incompatible operations, it's more likely that they will also want to revisit the endpoint naming too, so they'll just create new endpoints with new names. (instead of naming anything "v2").

Then, if the entire API needs to be reworked, it's more likely that the team will just decide to deprecate the entire service/API, and then launch a new and better service with a different name to replace it.

So in the end, it's really rare that any endpoints ever have "/v2" in the name. I've been in the industry 25 years and only once have I seen a service that had a "/v2" to go with its "/v1".

ks20482• 11 months ago

So in the end, it's really rare that any endpoints ever have "/v2" in the name.

This is an interesting empirical question - take the 100 most used HTTP APIs and see what they do for backward-incompatible changes and see what versions are available. Maybe an LLM could figure this out.

I've been just using the Dropbox API and it is, sure enough, on "v2". (although they save you a character in the URL by prefixing "/2/").

Interesting to see some of the choices in v1->v2,

https://www.dropbox.com/developers/reference/migration-guide

They use a spec language they developed called stone (https://github.com/dropbox/stone).

grodriguez1002• 11 months ago

The author does not say that you “should not add v1”. They say that versioning is how you change your API responsibly (so, endorsing versioning), but that you should only do it as a last resort.

So you would add “v1”, to be able to easily bump to v2 later if needed, and do your best to avoid bumping to v2 if at all possible.

gitremote• 11 months ago

I don't think the author meant they don't include /v1 in the endpoint in the beginning. The point is that you should do everything to avoid having a /v2, because you would have to maintain two versions for every bug fix, which means making the same code change in two places or having extra conditional logic multiplied against any existing or new conditional logic. The code bases that support multiple versions look like spaghetti code, and it usually means that /v1 was not designed with future compatibility in mind.

account424• 11 months ago

If you really care about maintaining v1 long-term you'd re-implement it as a small shim above v2.

pbreit• 11 months ago

Disagree. Baking versioning in from the start means they will much more likely be used, which is a bad thing.

grodriguez1002• 11 months ago

I would say the author recommends the same actually: they say that versioning is “how you change your API responsibly” (so, endorsing versioning), but that you should only switch to a new version as a last resort.

JimDabell7• 11 months ago

While the author doesn't seem to like version based APIs very much, I always recommend baking them in from the very start of your application.

You don’t really need to do that for REST APIs. If clients request application/vnd.foobar then you can always add application/vnd.foo.bar;version=2 later without planning this in advance.

946789987649• 11 months ago

If you use something like an OpenAPI generator and want to have different DTOs in your version 2, then you cannot do what you suggested.

lazyasciiart2• 11 months ago

Most REST APIs don’t support that. So you don’t need versioning for APIs that already have a request type specified.

9dev• 11 months ago

Actually, there’s nothing stopping you from using a custom "Version: 2" Header in requests and responses

spixy3• 11 months ago

The problem is with parameters (or headers) you are still stuck with same API schema (you cannot rename it, etc).

But thanks to versions, in my job we renamed old APIs like /v1/oauthApple and /v1/oauthGoogle to /v2/login/oauth/apple and /v2/login/oauth/google, looks so much better.

claw-el3• 11 months ago

However, a technically-poor product can make it nearly impossible to build an elegant API. That’s because API design usually tracks the “basic resources” of a product (for instance, Jira’s resources would be issues, projects, users and so on). When those resources are set up awkwardly, that makes the API awkward as well.

One issue I have with weird resources are those that feel like unnecessary abstraction. It makes it hard for the human to read and understand intuitively, especially someone new to these set of APIs. Also, it makes it so much harder to troubleshoot during an incident.

frabonacci• 11 months ago

The reminder to "never break userspace" is gold and often overlooked.. ahem Spotify, Reddit and Twitter come to mind.

runroader• 11 months ago

I think the only thing here that I don't agree with is that internal users are just users. Yes, they may be more technical - or likely other programmers, but they're busy too. Often they're building their own thing and don't have the time or ability to deal with your API churning.

If at all possible, take your time and dog-food your API before opening it up to others. Once it's opened, you're stuck and need to respect the "never break userspace" contract.

devmor• 11 months ago

I think versioning still helps solve this problem.

There’s a lot of things you can do with internal users to prevent causing a burden though - often the most helpful one is just collaborating on the spec and making the working copy available to stakeholders. Even if it’s a living document, letting them have a frame of reference can be very helpful (as long as your office politics prevent them from causing issues for you over parts in progress they do not like.)

Supermancho• 11 months ago

With internal users, you likely have instrumentation that allows you to contact and have those users migrate. You can actually sunset api versions, making API versioning an attractive solution. I've both participated in API versioning and observed it employed in organizations that don't use it by default as a matter of utility.

scott_w• 11 months ago

A big difference is you can tell internal users to update or else. It’s not free and should be reserved for good business reasons, but it can happen on a shorter time frame as you have the internal organisation to enforce it.

It’s not really an option in the same way with end users or customers, as they aren’t part of your organisation, by definition.

cyberax6• 11 months ago

I'm a bit of a different opinion on API versioning, but I can see the argument. I definitely disagree about idempotency: it's NOT optional. You don't have to require idempotency tokens for each request, but there should be an option to specify them. Stripe API clients are a good example here, they automatically generate idempotency tokens for you.

Things that's missing from this list but that were important for me at some points:

1. Deadlines. Your API should allow to specify the deadline after which the request is no longer going to matter. The API implementation can use this deadline to cancel any pending operations.

2. Closely related: backpressure and dependent services. Your API should be designed to not overload its own dependent services with useless retries. Some retries might be useful, but in general the API should quickly propagate the error status back to the callers.

3. Static stability. The system behind the API should be designed to fail static, so that it retains some functionality even if the mutating operations fail.

dwattttt• 11 months ago

The reminder to "never break userspace" is good, but people never bring up the other half of that statement: "we can and will break kernel APIs without warning".

It illustrates that the reminder isn't "never change an API in a way that breaks someone", it's the more nuanced "declare what's stable, and never break those".

chubot2• 11 months ago

Yeah, famously there is no stable public driver API for Linux, which I believe was the motivation for Google’s Fuschia OS

So Linux is opinionated in both directions - towards user space and toward hardware - but in the opposite way

matheusmoreira• 11 months ago

It's not just opinionation though. It's the kernel's leverage against the people who would keep their modules out of the git tree instead of contributing them. Those people literally get left behind and they are forced to pay maintainers to chase a continuously moving target. The solution to that is to contribute the code.

delta_p_delta_x2• 11 months ago

Even if the kernel doesn't break userspace, GNU libc does, all the time, so the net effect is that Linux userspace is broken regardless of the kernel maintainers' efforts. Put simply, programs and libraries compiled on/for newer libc are ABI-incompatible or straight-up do not run on older libc, so everything needs to be upgraded in lockstep.

It is a bit ironic and a little funny that Windows solved this problem a couple decades ago with redistributables.

Retr0id2• 11 months ago

otoh staticly-linked executables are incredibly stable - it's nice to have that option.

rcxdude2• 11 months ago

GNU libc has pretty good backwards compatibility, though, so if not you want to run on a broad range of versions, link against as old a version of libc as is practical (which does take some effort, annoyingly). It tends to be things like GUI libraries and such which are a bigger PITA, because they do break compatibility and the old versions stop being shipped in distros, and shipping them all with your app can still run into protocol compatibility issues.

o11c2• 11 months ago

You're describing 2 completely different things there.

If your program is built to require myfavoritelibrary version 1.9, and you try to run it against myfavoritelibrary 1.0, no shit it doesn't work. Glibc is no different than any other in this regard.

If your program is built to require myfavoritelibrary version 1.0, and you try to run it on myfavoritelibrary 1.9 ... glibc's binary compatibility story has been very good since the release of 2.2 or so, way back in 2000. (I know from documentation that there were a lot of 2.0 -> 2.1 breakages, some of which might've actually been fixed in 2.1.x point releases, so I'm saying 2.2 to be safe)

It's not quite as perfect as Linux's "we do not break userland" but it's pretty darn close; I would have to hunt down changelogs to find something that actually broke without explicitly relying on "do not rely on this" APIs. Source compatibility is a different story, since deprecated APIs can be removed from the public headers but still present in the binary.

... actually, even Linux has unapologetically broken its promise pretty badly in the past at various times. The 2.4 to 2.6 transition in particular was nasty. I'm also aware of at least one common syscall that broke in a very nasty way in some early versions; you can't just use ENOSYS to detect it but have to set up extra registers in a particular way to induce failure for incompatible versions (but only on some architectures; good luck with your testing!)

---

There's nothing stopping you from installing and using the latest glibc and libgcc at runtime, though you'll have to work around your distro's happy path. Just be careful if you're building against them since you probably don't want to add extra dependencies for everything you build.

By contrast, I have statically-linked binaries from ~2006 that simply do not work anymore, because something in the filesystem has changed and their version of libc can't be fixed the way the dynamically-linked version has.

brainzap• 11 months ago

makes me remember a Evan: we provided a migration path from 2 to 3, but so many internal changed that many plugins broke

hackrmn2• 11 months ago

In software engineering the statement "interfaces, not implementations" has been used for a long time (certainly at least Robert "Uncle Bob" C. Martin started teaching), which is a generalization on the "we don't break userspace". In essence it cooks down to declaring an interface without announcing or depending on the implementation. With OOP languages like C++, a code base would aggressively use interfaces as types, never concrete class types (which implement the interface), so that it can make it easier to reason about how and whether the program behaves when one implementation of an interface is swapped for another.

With Linux, which is a C codebase by and large, they load and pass pointers to structures to kernel procedures which can do as they please -- as long as the documentation on said structures (which usually says which fields and how are retained with which values and so on) remains unchanged. That's their "object oriented programming" (yeah, I know Linus would likely have hated the comparison).

zahlman3• 11 months ago

Anyone else old enough to remember when "API" also meant something that had nothing to do with sending and receiving JSON over HTTP? In some cases, you could even make something that your users would install locally, and use without needing an Internet connection.

drdaeman• 11 months ago

I believe it’s pretty common to e.g. call libraries’ and frameworks’ user- (developer-) facing interface an API, like in “Python’s logging library has a weird-looking API”, so I don’t think API had eroded to mean only networked ones.

mettamage2• 11 months ago

I never understood why libraries also had the word API. From my understanding a library is a set of functions specific to a certain domain, such as a statistics library, for example. Then why would you need the word API? You already know it’s a library.

For end points it’s a bit different. You don’t know what are they or user facing or programmer facing.

I wonder if someone has a good take on this. I’m curious to learn.

chubot2• 11 months ago

Well it stands for “application programming interface”, so I think it is valid to apply it to in-process interfaces as well as between-process interfaces

Some applications live in a single process, while others span processes and machines. There are clear differences, but also enough in common to speak of “APIs” for both

zahlman3• 11 months ago

It certainly is valid. I'm just irritated that it's taken over to the extent that it has.

Just as I am irritated that people seem to have forgotten that "applications" can potentially run completely locally, and that programs can be designed around the assumption that the "front end" (UI) and "back end" (business logic) will communicate directly (or at least exist within the same process, even if there are good reasons to set up message queues etc.).

But, you know, that's bad for business. Because that entails that the consumer might actually get to own something, even if it's just an ephemeral pattern of bits on local storage.

17186274402• 11 months ago

In my knowledge, there is the distinction of API vs. protocol, i.e. whether you use the foreign software through calling into it or by serializing and sending somewhere. "web APIs" seam to be the latter not the former, so I don't get why they got christened APIs.

rogerthis• 11 months ago

Things would come in SDKs, and docs were in MS Help .chm files.

j452• 11 months ago

APIs are for providing accessibility - to provide access to interactions and data inside an application from the outside.

The format and protocol of communication was never fixed.

In addition to the rest api’s of today, soap, wsdl, web sockets could all can deliver some form of API.

bigiain• 11 months ago

CORBA

Shudder...

gct• 11 months ago

Everyone's decided that writing regular software to run locally on a computer is the weird case and so it has to be called "local first".

ivanjermakov• 11 months ago

sending and receiving JSON over HTTP

In my circles this is usually (perhaps incorrectly) called REST API.

mlhpdx• 11 months ago

Having built a bunch of low level network APIs I think the author hits on some good, common themes.

Versioning, etc. matter (or don’t) for binary UDP APIs (aka protocols) just as much as for any web API.

wener• 11 months ago

I still try think /v1 /v2 is a break, I don't trust you will keep v1 forever, otherwise you'll never introduce this execuse.

I'd like to introduce more fields or flags to control the behavior as params, not asking user to change the whole base url for single new API.

calrain• 11 months ago

I like this pattern.

When an API commits to /v1 it doesn't mean it will deprecate /v1 when /v2 or /v3 come out, it just means we're committing to supporting older URI strategies and responses.

/v2 and /v3 give you that flexibility to improve without affecting existing customers.

swagasaurus-rex• 11 months ago

Cursor based pagination was mentioned. It has another useful feature: If items have been added between when a user loads the page and hits the next button, index based pagination will give you some already viewed items from the previous page.

Cursor based pagination (using the ID of the last object on the previous page) will give you a new list of items that haven't been viewed. This is helpful for infinite scrolling.

The downside to cursor based pagination is that it's hard to build a jump to page N button.

echelon2• 11 months ago

You should make your cursors opaque so as to never reveal the size of your database.

You can do some other cool stuff if they're opaque - encode additional state within the cursor itself: search parameters, warm cache / routing topology, etc.

rockwotj2• 11 months ago

Came here to say these same things exactly. Best write up I know on this subject: https://use-the-index-luke.com/sql/partial-results/fetch-nex...

0xbadcafebee• 11 months ago

Most people who see "API" today only think "it's a web app I send a request to, and I pass some arguments and set some headers, then check some settings from the returned headers, then parse some returned data."

But "API" means "Application Programming Interface". It was originally for application programs, which were... programs with user interfaces! It comes from the 1940's originally, and wasn't referred to for much else until 1990. APIs have existed for over 80 years. Books and papers have been published on the subject that are older than many of the people reading this text right now.

What might've those older APIs been like? What were they working with? What was their purpose? How did those programmers solve their problems? How might that be relevant to you?

spacechild12• 11 months ago

You are talking in past tense, but there are still many non-web APIs. Every software library has an API. I still find it incredibly annoying that the web folks have hijacked the term "API" as a short hand for "web API".

stronglikedan• 11 months ago

the web folks have hijacked the term "API" as a short hand for "web API".

I don't see it. API is too vague to mean one type of API, whether it's one from before the web, or a web API. As soon as there was more than one type of API, the term API became incomplete without a qualifier. Nothing was hijacked, and your sentence includes an incomplete term.

fanf2• 11 months ago

It comes from the 1940's originally

Really?! That’s amazingly early. There were barely even subroutine libraries at that time. I’d love to see an example of "Application Programming Interface" from that time.

(I don’t remember seeing the term until Microsoft started using it when talking about Windows in the 1990s; before then it was things like library functions or supervisor calls - but I didn’t have much experience at that point so I was probably missing some of the more collar-and-tie programmer lingo.)

17186274402• 11 months ago

You are talking as if it were a thing of a past. Yet I am 20 and when I read API, only ever think of it as in API/ABI. I don't think a protocol endpoint is an API.

achernik• 11 months ago

How should you store the key? I’ve seen people store it in some durable, resource-specific way (e.g. as a column on the comments table), but I don’t think that’s strictly necessary. The easiest way is to put them in Redis or some similar key/value store (with the idempotency key as the key).

I'm not sure how would storing a key in Redis achieve idempotency in all failure cases. What's the algorithm? Imagine a server handling the request is doing a conditional write (like SET key 1 NX), and sees that the key is already stored. What then, skip creating a comment? Can't assume that the comment had been created before, since the process could have been killed in-between storing the key in Redis and actually creating the comment in the database.

An attempt to store idempotency key needs to be atomically committed (and rolled back in case it's unsuccessful) together with the operation payload, i.e. it always has to be a resource-specific id. For all intents and purposes, the idempotency key is the ID of the operation (request) being executed, be it "comment creation" or "comment update".

rockwotj2• 11 months ago

Yes please don’t add another component to introduce idempotency, it will likely have weird abstraction leaking behavior or just be plain broken if you don’t understand delivery guarantees. Much better to support some kind of label or metadata with writes so a user can track progress on their end and store it alongside their existing data.

spixy3• 11 months ago

Algorithm is that the key is changed everytime after result 200 from API or page is refreshed or changed to another.

canpan• 11 months ago

many of your users will not be professional engineers. They may be salespeople, product managers, students, hobbyists, and so on.

This is not just true for authentication. If you work in a business setting, your APIs will be used by the most random set of users. They be able to google for how to call your api in python, but not be able to do things like converting UTC to their local time zone.

barapa• 11 months ago

They suggest storing the idempotency key in redis. Seems like if possible, you should store them in whatever system you are writing to in a single transaction with the write mutations.

tiffanyh• 11 months ago

Here’s also some good recommendations: https://jcs.org/2023/07/12/api

JimDabell7• 11 months ago

That’s good too. Regarding:

Be descriptive in your error responses

This is a useful standardised format:

RFC 7807: Problem Details for HTTP APIs

— https://datatracker.ietf.org/doc/html/rfc7807

JimDabell7• 11 months ago

This is great. One thing I would add:

The quality of the API is inversely correlated to how difficult it is to obtain API documentation. If you are only going to get the API documentation after signing a contract, just assume it’s dismally bad.

rubenvanwyk• 11 months ago

This. It usually also means no OpenAPI standards, which makes integration much more difficult.

josevalerio• 11 months ago

Sometimes you get the docs emailed in a password protected spreadsheet :')

mrkeen• 11 months ago

That way you can send as many retries as you like, as long as they’ve all got the same idempotency key - the operation will only be performed once.

I worked in an org where idempotency meant: if it threw an exception this time, it needs to throw the same exception everytime.

cjblomqvist• 11 months ago

Pragmatism rules here, but yeah - the common way to do this (at least if you have keys generatable by the client), eg. using REST, is to not allow POSTs, but only PUT. Most APIs I've seen use PUT solely for updates (of existing items), but as is obvious from the wording it's not the original intention.

deterministic• 11 months ago

It’s rare to read an article where I agree 100% with everything written.

Bravo!

jillesvangurp• 11 months ago

API versioning mostly just means things perpetually stuck at v1. You might have the intention to change things up, but you never will.

Putting version numbers in a URL is a bit of a kludge. v1 is the most common version, by far, you will ever see in a url. v2 is rare. v3 is more common strangely. I don't think I've seen a v4 or v5 or higher in the wild very often. That's just not a thing.

My theory is that v1 is the quick and dirty version that developers would like to forget exists. v2 is the "now we know what we're doing!" version and that's usually quickly followed by v3 because if you can change your mind once you can do it twice. After which people just tell developers to quit messing with the API already and keep things stable. v4 and v5 never happen.

Another observation is that semantic versioning for API urls here seems rare. Reason: it's inconvenient for clients to have to update all their URLs every time some developer changes their mind. Most clients will hard code the version. Because it never changes. And because it is hard coded, changing the version becomes inconvenient.

My attitude towards URL based versioning is that you could do it but it's not a tool that you get to use much. Therefore you can safely skip it and it won't be a problem. And in the worst case where you do need it, you can easily add a v2 URL space anyway. But you probably never will as you are unlikely to deprecated the entirety of your API.

There are other ways to deal with deprecating APIs. You can just add new paths or path prefixes in your API as needed. You can use a different domain. Or you can just remove them after some grace period. It depends. Versioning is more aspirational than actually a thing with APIs.

We do version our API but via client headers. Our API client sends a version header. And we check it server side and reject older versions with a version conflict response (409). This enables us to force users of our app to update to something we still support. The version number of our client library increments regularly. Anything falling behind too far we reject. This doesn't work for all use cases. But for a web app this is completely fine.

shrx• 11 months ago

Discord API [0] currently defaults to version 6, with version 10 being already available.

[0] https://discord.com/developers/docs/reference

spixy3• 11 months ago

You can do fallback so that {no version} endpoint points to v1 endpoint (/auth/login and /v1/auth/login are the same).

That way you have versioning and also simple urls.

TrueSlacker0• 11 months ago

There is always an outlier, but Quickbooks is currently on minor version 75.

deathanatos• 11 months ago

Pagination: do not force me to drink from a paginated coffee stir. I do not want 640 B of data in a response, and then have to send another response for the next 640 B. And often, pagination means the calls are serialized, so I'm just doing nothing but waiting for round trip latency after round trip latency for the next meager 640 B of data.

Azure I'm looking at you. Many of their services do this, but Blob storage is something else: I've literally gotten information-free responses there. (I.e., 0 B of actual data. I wish I could say 0 B were used to transfer it.)

When you're designing, think about how big a record/object/item is, and return a reasonable number of them in a page. For programmatic consumers who want to walk the dataset, a 640 KiB response is really not that big, and I've seen so many times responses orders of magnitude less, because someone thought "100 items is a good page size, right?" and 100 items was like 4 KiB of data.

If you have thirty API endpoints, every new version you add introduces thirty new endpoints to maintain. You will rapidly end up with hundreds of APIs that all need testing, debugging, and customer support.

You version the one thing that's changing.

As much as I hate the /v2/... form of versioning, nobody reversions all the /v1/... APIs just because one API needed a /v2. /v2 is ghost town, save for the /v2 APIs.

atoav2• 11 months ago

Yeah, pagination ia a great option — maybe even a good default. But don't make it the only choice, give developers the choice to make the tradeoff between number of requests and payload size.

rirze• 11 months ago

I'm curious, is there a backend reason to only offer pagination? Is it less work on the backend vs a user making X calls to get all the resources anyways?

mulholio• 11 months ago

It’s certainly been my experience that page sizes should be bigger than you initially expect. Paginated endpoints are typically iterated all the way through meaning you’re going to return that data anyway. May as well save the additional overhead from multiple requests.

Not implementing pagination at the outset can be problematic, however. If you later want to paginate data (e.g. if the size of your data grows) then it’s going to be a breaking change to implement that later. Big page sizes but with pagination can be a reasonable balance.

miki123211• 11 months ago

You should let people use your APIs with a long-lived API key

This is an extremely unpopular opinion, but I would go even further. I think you should let people use your API with just an username and a password.

It should by no means be the only way people can use your API. Put very low users-per-IP rate limits on that approach if you want to, to force lazy but professional software developers to go the oAuth route before their app gets to production. For one-off scripts though, APIs that let you do this are a breath of fresh air.

If your API is based on API keys, you will be tempted to do things that really annoy new users of that API. People don't want to tell you what their app name is, they don't know that yet. They're certainly not picking a purpose they need this API for from a list of five, not if it doesn't include "completing a classroom assignment I don't really care about and want to finish as quickly as possible." They for sure don't yet know what scopes they might possibly need, even if to you, their names are descriptive and obvious. If you allow user-password authentication, you take away the ability to shoot yourself in the foot in this way.

minzak• 11 months ago

Nice article. I'd also highly recommend "How To Design A Good API and Why it Matters" video from Joshua Bloch (co-author of Java). He digs much deeper, mostly at code level rather than JSON level but the same principles apply. Even though this video is almost 20 years old, the topics are as significant today as they were back then. https://www.youtube.com/watch?v=aAb7hSCtvGw

weinzierl• 11 months ago

"Think about it - if you send three DELETE comments/32 requests in a row, it won’t delete three comments. The first successful request will delete the comment with ID 32, and the remaining requests will 404 when they can’t find the already-deleted comment."

Not necessarily. Many implementations return HTTP 204 for any DELETE that succeeds in the sense that the element is gone regardless if it had been there before. To me this always made much more sense than 404.

gbrits• 11 months ago

Indeed. Extending idempotency to the response not merely the action wherever possible

account424• 11 months ago

But why? Now the client has strictly less information than it had before.

The client already has the capability to handle 404 for DELETEs.

BrainyZeiny• 11 months ago

In 2025, leaving GraphQL out of a discussion on modern API design is like writing about web frameworks and downplaying React. It may not be right for every use case.. but it has become foundational in many serious frontend/backend architectures, and that deserves acknowledgment.

GraphQL isn’t just another protocol. It’s a paradigm shift in how we think about designing and consuming APIs. The author downplays its role, but in practice, GraphQL enables cleaner contracts between frontend and backend, encourages typed schemas, and dramatically reduces over-fetching and under-fetching. That’s not a minor point .. that’s central to what most developers care about when consuming APIs.

Regarding caching: yes, REST has traditional browser and CDN-based caching, but GraphQL is absolutely cacheable too. Tools like Apollo Client and Relay have built-in normalized caches that are far more granular and powerful than most REST setups. At the infrastructure level, persisted queries and CDN layer solutions (like GraphCDN or Stellate) further optimize caching behavior. So the claim that “you can’t cache GraphQL” is outdated at best.

nevertoolate• 11 months ago

Caching is straw-man. Complexity tends to be higher to implement a graphql backend than for e.g. type-spec => openapi backend. For the simple case the simpler solution wins imo. For the complex case it can be a toss-up, but it seems that performance and security can be a big deal-breaker for graphql, so maybe only big enterprises can afford to go down that route.

I'm not sure what you mean by the react analogy, react seems to be far more popular than graphql in their respective areas.

VGHN7XDuOXPAzol2• 11 months ago

GraphQL has some impressive points, but sometimes feels like it shifts too much control to the client. I'm on the fence about it.

There are performance footguns (like recursion, for which you'd have to consult your GraphQL server library for mitigations). There is often a built-in 'introspection' endpoint, which many consider a security faux-pas (to which I disagree — I think it's pretty noble, like having built-in OpenAPI docs) BUT you can easily craft a recursive query using just this endpoint that will take (some) GraphQL servers down. There are plenty of posts written on the matter and I'm sure there are mitigations, but my first exposure to GraphQL was on someone else's project (a respectable engineer who I consider very skilled) and within the first day I had noticed this intriguing structural hazard and taken the server down...

It therefore seems to be a tool that is possibly difficult to 'hold correctly'; at least people should be cautious about going in without doing their research about these things. Probably a maturity issue, but one that people ought to be aware of?

Other gripes:

It's displeasing how the HTTP status code does not correlate with the actual success response of the API, which makes typical request logging less useful.

I guess it also makes it harder to provide optimised hot paths on the server (because your client team might shift their queries around, or whatever).

In previous experience I also find that having easily-recognisable names for API endpoints (like `GET /repositories`) makes talking about them, and recognising them, easier than the more-opaque-feeling GraphQL approach.

randallsquared• 11 months ago

I don't really understand why you'd bring up DELETE in a passage about idempotence and not PUT.

Joker_vD2• 11 months ago

Instead of using OFFSET, the query becomes WHERE id > cursor ORDER BY id LIMIT 10

Wait. Surely "ORDER BY id OFFSET 20 LIMIT 10" works about the same as "WHERE id > cursor ORDER BY id LIMIT 10", if "id" is indexed?

asddubs• 11 months ago

no, because it has to count the amount of matching rows preceding the offset rows to determine the offset, i.e. iterate over all preceding rows. The cursor provides a starting point for the offset so in this instance it's not necessary.

https://use-the-index-luke.com/sql/partial-results/fetch-nex...

Joker_vD2• 11 months ago

It only has to count if the index doesn't store the amounts of records in the "chunks" it manages, does it? I'm pretty sure B-trees do actually store the sizes of the subtrees.

sushrut1058• 11 months ago

Great article!

dev_l1x_be• 11 months ago

Sean Goedecke's blog posts become my foundation folder for prompting LLMs to design new systems. He captures so much with few blog posts, incredible.

hackrmn2• 11 months ago

I've always been a staunch opponent of using `/v1/` kind of element in the URL. I understand its function and the convenience it allows for "versioning", but I grew up with HTTP and I always liked how it insisted the URL is well, the _location_ of the _resource_, and `/v1/` just muddies things up being in the URL -- it's obviously not a version of the resource that `/v1/` would be indicating, but of the API implementation, which is the first telltale sign that it's an architectural "blunder", and these compound in my experience, always and invariably given enough time.

If the consumer wants to consume a specific version of the API, the means to do so can be implemented with an alternative domain name, or -- even better (who wants to maintain alternative domain names) -- with a request _header_, e.g. `X-API-Version: v1` (or another one, perhaps a standardised one).

In any case, the `/v1/` thing is something of cargo cult programming -- I remember someone proposed it a good while ago, and it's been adopted since without much afterthought, it seems. It doesn't make sense to debate pros and cons of REST/HATEOAS if your resource identifier scheme is poorly designed, IMO.

Everything I know about good API design

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