Harper – an open-source alternative to Grammarly

        "PointIsMoot" => (
            ["your point is mute"],
            ["your point is moot"],
            "Did you mean `your point is moot`?",
            "Typo: `moot` (meaning debatable) is correct rather than `mute`."
        ),

a2128• 1 year ago

From a quick look phrase corrections is just one type of rule. There are many other rules, some are dynamic like when to use "your" vs "you're", oxford commas, etc.

That it doesn't use LLMs is its advantage, it runs in under 10ms and can be easily embedded in software and still provide useful grammar checking even if it's not exhaustive

VTimofeenko• 1 year ago

Comes with a great LSP server capable of checking grammar in code comments:

https://writewithharper.com/docs/integrations/language-serve...

pram• 1 year ago

IMO not using LLMs is a big plus in my book. Grammarly has been going downhill since they've been larding it with "AI features," it has become remarkably inconsistent. It will tell me to remove a comma one hour, and then tell me to add it back the next.

raincole• 1 year ago

So is there a similar tool but based on an LLM?

Not that I think LLM is always better, but it would be interesting to compare these two approaches.

7thaccount• 1 year ago

Grammarly came out before the LLMs. I'm not sure what approach it took, but they're likely feeling a squeeze as LLMs can tell you how to rewrite a sentence to remove passive voice and all that. I doubt the LLMs are as consistent (some comments below show some big issues), but they're free (for now).

mannycalavera42• 1 year ago

Grammarly is (was) written in Common LISP https://www.grammarly.com/blog/engineering/running-lisp-in-p...

Given LISP was supposed to build "The AI" ... pretty sad than a dumb LLM is taking its place now

chneu• 1 year ago

Thank you. In general my grammarly and gboard predictions have become so, so bad over the last year.

boplicity• 1 year ago

General purpose LLMs seem to get very confused about punctuation, in my experience. It's one of their big areas of obvious failing. I'm surprised Grammarly would allow this to happen.

jethro_tell• 1 year ago

The internet, especially post phone keyboards, is extremely inconsistent about punctuation. I’m not sure how anyone could think an llm wouldn’t be.

raverbashing• 1 year ago

It will tell me to remove a comma one hour, and then tell me to add it back the next.

So just like English teachers I see

InsideOutSanta4• 1 year ago

Grammarly sometimes gets stuck in a loop, where it suggests changing from A to B. It then immediately suggests changing from B to A again, continuing to suggest the opposite change every time I accept the suggestion.

It's not a problem; I make the determination which option I like better, but it is funny.

tiew9Vii• 1 year ago

Being dyslexic, I was an avid Grammarly user. Once it started adding "AI features" the deterioration was noticeable, I cancelled my subscription and stopped using it a year ago.

I also only ever used the web app, so copy+pasting as installing the app is for all intentness and purposes is installing a key logger.

Grammar works on rules, not sure why that needs an LLM, Grammarly certainly worked better for me when it was more dumb, using rules.

Alex-Programs• 1 year ago

DeepL Write was pretty good in the post-LLM, pre-ChatGPT era.

Dr4kn• 1 year ago

DeepL is different in my opinion. They always focused on machine learning for languages.

They must have acquired fantastic data for their Models. Especially because of the business language and professional translations which they focus on.

They keep your intended message in tact and just refine it. Like a book post editing. Grammarly and other tools force you to sound like they think is best.

DeepL shows, in my opinion, how much more useful a model trained for specific uses is.

harvey92• 1 year ago

'imo' and 'in my book' are redundant in the same sentence. Are there rules-based techniques to catch things like that? Btw I loved the use of 'larding' outside the context of food.

jacooper• 1 year ago

I think if you can self host language tool, it would still be the better option.

demarq• 1 year ago

"Me and Jennifer went to have seen the ducks cousin."

No errors detected. So this needs a lot of rule contributions to get to Grammarly level.

wellthisisgreat• 1 year ago

What the duck is that test

canyp2• 1 year ago

Nominative vs objective

alpb• 1 year ago

Similarly 0 grammatical errors flagged: "My name John. What your name? What day today?"

Tsarp• 1 year ago

I was initially impressed. But then I tested a bunch, it wasn't catching some really basic things. Mostly hit or miss.

marginalia_nu2• 1 year ago

Goes the other way around too. For

In large, this is _how_ anything crawler-adjacent tends to be

It suggests

In large, this is how _to_ anything crawler-adjacent tends to be

The-Ludwig2• 1 year ago

Looks awesome! I’ll give it a try over language tool.

Is there any reason why there is no firefox extension?

chilipepperhott4• 1 year ago

There is!

https://addons.mozilla.org/en-US/firefox/addon/private-gramm...

The-Ludwig2• 1 year ago

Awesome! Thank you :)

thr0waway001• 1 year ago

“Yo who dis?”

Passes.

For reference: https://youtu.be/w-R_Rak8Tys?si=h3zFCq2kyzYNRXBI

IceWreck• 1 year ago

Slightly controversial compared to other comments here but I haven't used Grammerly at all since LLMs came out. Even a 4B local LLM is good enough to rephrase all forms of text and fix most grammer mistakes.

gglanzani• 1 year ago

I think a lot of value comes by integrating with a language server and/or browser extensions.

Do you have a setup where this is possible or do you copy paste between text fields? (Genuine question. I’d love to use a local LLM integrating with an LSP).

orliesaurus• 1 year ago

Very buggy, but great start!!

I.e. if you write an "MISTAEK" and then you scroll the highlight follows me around the page

crimputer• 1 year ago

Good start. But still has bugs i guess.

I tried with the following phrase -- "This should can't logic be done me." --

No errors.

harper• 1 year ago

nice name!

icapybara• 1 year ago

Why wouldn't you want an LLM for a language learning tool? Language is one of things I would trust an LLM completely on. Have you ever seen ChatGPT make an English mistake?

Groxx• 1 year ago

uh. yes? it's far from uncommon, and sometimes it's ludicrously wrong. Grammarly has been getting quite a lot of meme-content lately showing stuff like that.

it is of course mostly very good at it, but it's very far from "trustworthy", and it tends to mirror mistakes you make.

perching_aix• 1 year ago

Do you have any examples? The only time I noticed an LLM make a language mistake was when using a quantized model (gemma) with my native language (so much smaller training data pool).

healsdata3• 1 year ago

Grammarly is all in on AI and recently started recommended splitting "wasn't" and added the contraction to the word it modified. Example: "truly wasn't" becomes "was trulyn't"

https://imgur.com/a/RQZ2wXA

o11c• 1 year ago

Hm ... I wonder, is Grammarly also responsible for the flood of contraction of lexical "have" the last few years? It's standard in British English, but outside of poetry it is proscribed in almost all other dialects (which only permit contraction of auxiliary "have").

Even in British I'm not sure how widely they actually use it - do they say "I've a car" and "I haven't a car"?

akdev1l• 1 year ago

This is what peak innovation looks like

Destiner• 1 year ago

I don't think an LLM would recommend an edit like that.

Has to be a bug in their rule-based system?

marginalia_nu2• 1 year ago

I wonder how much memes like whomst'd might skew the training set.

dartharva2• 1 year ago

Because this "language learning tool" will be dominantly used to avoid actually learning the language.

InsideOutSanta4• 1 year ago

Yeah, I agree. An open-source LLM-based grammar checker with a user interface similar to Grammarly is probably what I'm looking for. It doesn't need to be perfect (none of the options are); it just needs to help me become a better writer by pointing out issues in my text. I can ignore the false positives, and as long as it helps improve my text, I don't mind if it doesn't catch every single issue.

Using an LLM would also help make it multilingual. Both Grammarly and Harper only support English and will likely never support more than a few dozen very popular languages. LLMs could help cover a much wider range of languages.

Szpadel• 1 year ago

I tried to use one LLM based tool to rewrite sentence in more official corporate form, and it rewrote something like "we are having issues with xyz" into "please provide more information and I'll do my best to help".

LLMs are trained so hard to be helpful that it's really hard to contain them into other tasks

behnamoh• 1 year ago

I wish it had keyboard shortcuts. As a Vim user, in Chrome it's tedious to click on every suggestion given by the app. Also, maybe add a "delay" so it doesn't think the currently-being-typed word is a mistake (let me finish typing first!).

Otherwise, it's great work. There should be an option to import/export the correction rules though.

healsdata3• 1 year ago

Given this is an Automattic product, I'm hesitant to use it. If it gets remotely successful, Matt will ruin it in the name of profit.

josephcsible• 1 year ago

It's FOSS, so even if the worst happens, anyone could just fork the last good version and continue development there.

jantissler• 1 year ago

Oh, that’s a big no from me then.

cAtte_• 1 year ago

this solution is just fundamentally insufficient. in the age of LLMs it's pretty insane to imagine programmers manually hard-coding an arbitrary subset of grammatical corrections (sure: it's faster, it's local first, but it's not enough). on top of that, English (like any other natural language) is such a complicated beast that you will never write a classic deterministic parser that's sophisticated enough to allow you to reliably implement even the most basic of grammatical corrections (check the other comments for examples). it's just not gonna happen.

i guess it's a nice and lightweight enhancement on top of the good old spellchecker, though

paxys• 1 year ago

Looks cool, but it's weird to constantly make comparisons to Grammarly (in the post title, description section of the site, benchmarks) when this is clearly a rule-based spellcheck and very different from what Grammarly offers.

Instead tell me how it compares to the built-in spellcheck in my browser/IDE/word processor/OS.

tolerance2• 1 year ago

I would much rather check my writing against grammatical rules that are hard coded in an open source program—meaning that I can change them—than ones that I imagine would be subject to prompt fiddling or worse; implicitly hard coded in a tangle of training data that the LLM would draw from.

The Neovim configuration for the LSP looks neat: https://writewithharper.com/docs/integrations/neovim

The whole thing seems cool. Automattic should mention this on their homepage. Tools like this are the future of something.

triknomeister• 1 year ago

You would lose out on evolution of language.

phoe-krk6• 1 year ago

Natural languages evolve so slowly that writing and editing rules for them is easily achievable even this way. Think years versus minutes.

airstrike• 1 year ago

I don't need grammar to evolve in real time. In fact, having a stabilizing function is probably preferable to the alternative.

eadmund• 1 year ago

If a language changes, there are only three possible options: either it becomes more expressive; or it becomes less expressive; or it remains as expressive as before.

Certainly we would never want our language to be less expressive. There’s no point to that.

And what would be the point of changing for the sake of change? Sure, we blop use the word ‘blop’ instead of the word ‘could’ without losing or gaining anything, but we’d incur the cost of changing books and schooling for … no gain.

Ah, but it’d be great to increase expressiveness, right? The thing is, as far as I am aware all human languages are about equal in terms of expressiveness. Changes don’t really move the needle.

So, what would the point of evolution be? If technology impedes it … fine.

Polarity• 1 year ago

why did you use chatgpt for this text then?

acidburnNSA• 1 year ago

I can write em-dashes on my keyboard in one second using the compose key: right alt + ---

shortformblog2• 1 year ago

LanguageTool (a Grammarly competitor) is also open source and can be managed locally:

https://github.com/languagetool-org/languagetool

I generally run it in a Docker container on my local machine:

https://hub.docker.com/r/erikvl87/languagetool

I haven't messed with Harper closely but I am aware of its existence. It's nice to have options, though.

It would sure be nice if the Harper website made clear that one of the two competitors it compares itself to can also be run locally.

akazantsev2• 1 year ago

There are two versions of the LanguageTool: open source and cloud-based. Open source checks the individual words in the dictionary just like the system's spell checker. Maybe there is something more to it, but in my tests, it did not fix even obvious errors. It's not an alternative to Grammarly or this tool.

shortformblog2• 1 year ago

There is. It can be heavily customized to your needs and built to leverage a large ngram data set:

https://dev.languagetool.org/finding-errors-using-n-gram-dat...

I would suggest diving into it more because it seems like you missed how customizable it is.

unfitted2545• 1 year ago

This is a really nice app to use LanguageTool, it runs the server in the flatpak: https://flathub.org/apps/re.sonny.Eloquent

dartharva2• 1 year ago

I never understood the appeal of grammar tools. If you have reached the minimum professional/academic level needed to be designated to write something, shouldn't you at least be capable of verifying its semantic "correctness" just by reading through it once yourself?

Why would you pass a writing job to someone who isn't 100% fluent in the language and then make up for it by buying complex tools?

Semaphor• 1 year ago

I use it (well, languagetool) in the free version for comments on sites like this. It directly catches mistakes I make, that I'd normally only catch on re-reads. From typos, over my brain doing weird stuff, to sometimes things I simply didn't (actively) know.

facundo_olano• 1 year ago

As a non native English speaker/writer there are a bunch of errors I miss, no matter how much attention I pay and how much I proofread, and these tools are useful to catch those.

speedgoose• 1 year ago

Have you considered that some people aren’t 100% fluent in English but still competent?

victorbjorklund3• 1 year ago

I know for example David Sparks (MacSparky https://www.macsparky.com ) uses it (or at leased used it). And he was an American lawyer and he says writing has been his passion his whole life so I assume his English is better than the average person.

Veen2• 1 year ago

People are bad at proofreading their own work. Professional writers often use third-party copy editors and proofreaders for that reason.

Finnucane2• 1 year ago

I’m a production editor at an uni press, and I can tell you there’s not a strong correlation between professional/academic level and writing well.

jordanpg• 1 year ago

I'm a lawyer. I write 10s of pages of text every day. "Reading through it once yourself" is obviously an imperfect solution. See, e.g., Poisson statistics. It's also slow and I bill in 6-minute increments. There is significant value in a grammar tool that protects confidentiality and is more effective than my wetware.

raybb• 1 year ago

Would be nice if they had a website where you could demo/test it before downloading extensions and stuff. Their firefox extension opens to this page https://writewithharper.com/install-browser-extension but when you paste in anything more than a few paragraphs the highlighting is all messed up.

lurk2• 1 year ago

Who is the target market is for Grammarly? Working professionals who speak English as a second language?

m00dy• 1 year ago

People who haven't heard of LLMs

akazantsev2• 1 year ago

LLMs are not nice to use for spell checking. I do not want to read a wall of text from LLM just to find a missed article somewhere and I want to receive feedback as I type.

Also, once I asked LLM to check the message. It said everything looked fine and made a copy of the message in its response with one sentence in the middle removed.

victorbjorklund3• 1 year ago

I think it is anyone who wanna make sure they write correctly. I know for example David Sparks (MacSparky https://www.macsparky.com ) uses it (or at leased used it). And he was an American lawyer and he says writing has been his passion his whole life so I assume his English is better than the average person.

InsideOutSanta4• 1 year ago

Adam Engst from TidBITs, a person whose job has been writing things for all his life, also uses Grammarly:

https://tidbits.com/2025/01/30/why-grammarly-beats-apples-wr...

InsideOutSanta4• 1 year ago

“Think of how poorly the average person writes, and realize half of them write worse than that.”

(George Carlin or something, quote's veracity depends on what you mean by “average.”)

I think everybody could benefit from having something like Grammarly on their computer. None of us writes perfectly, and it's always beneficial to strive for improvement.

Veen2• 1 year ago

I use it as a proofreader, not to improve my writing. It’s difficult to proofread your own work, and Grammarly is a useful assistant. Plus, I’m British and I often write on behalf of American clients. I’m pretty good at following US English standards because I’ve been doing it for a long time, but the odd Britishism slips through and Grammarly usually catches it (although a standard spell checker would too, I suppose).

pragmatick• 1 year ago

"For most documents, Harper can serve up suggestions in under 10ms." 10l is OK. 10kg as well. Why is 10ms wrong?

ibobev• 1 year ago

I'm a long-time Grammarly user. I just tried Harper, and it simply performs very poorly. It is a good initiative, but I don't feel the current state of this software to be worthwhile.

victorbjorklund3• 1 year ago

Very cool. Has anyone integrated this into their own app? How was your experience?

EugeneOZ• 1 year ago

Great! Please create an iOS keyboard with Harper

v5v3• 1 year ago

I used to see ads for Grammarly and wondered if anyone was using it.

Then post COVID with the increase in screen sharing video calls, I soon realised nearly every non-native English speaker from countries around the world heavily relied on it in their jobs. As I could see it installed when people share screens.

Huge market, good luck.

klabetron• 1 year ago

Odd choice that the example text on the homepage is almost all obvious typos that a standard spell check would pick up.

ErrorNoBrain• 1 year ago

Great to hear

i honestly don't trust grammarly ... i mean, its essentially a keylogger.

i did try it a bit once, and i never seem to have it work that well for me. But i am multilingual so maybe thats part of my hurdle

boars_tiffs• 1 year ago

vim plug?

chilipepperhott4• 1 year ago

There's an LSP. Not sure if that fits your use-case, though.

jimaek• 1 year ago

I don't understand why we even need such services. Why don't the browsers and maybe even the OS just not improve their included grammar checkers?

The Chrome enhanced grammar checker is still awful after decades.

Maybe the AI hype will finally fix this? I'm still surprised this wasn't the first thing they did.

piperly• 1 year ago

Unfortunately, the last time I tested Harper inside Neovim, it alone used more than 1 GB of RAM for just the LSP! However, the concept is nice, open source, no AI, and easy to integrate.

AbstractH24• 1 year ago

My biggest problem with Grammarly has always been how buggy the product is. From not checking random sites to messing up formatting to not updating text with the selected changes.

If Harper does better at this I’d change in a minute.

mpaepper• 1 year ago

Are languages other than English also supported? Or is this for English only?

ssernikk• 1 year ago

From their FAQ:

We currently only support English and its dialects British, American, Canadian, and Australian. Other languages are on the horizon, but we want our English support to be truly amazing before we diversify.

Finnucane2• 1 year ago

No serial comma? Screw that.

oersted2• 1 year ago

Fantastic work, I was so fed up with Grammarly and instantly installed this.

I'm just a bit skeptical about this quote:

Harper takes advantage of decades of natural language research to analyze exactly how your words come together.

But it's just a rather small collection of hard-coded rules:

https://docs.rs/harper-core/latest/harper_core/linting/trait...

Where did the decades of classical NLP go? No gold-standard resources like WordNet? No statistical methods?

There's nothing wrong with this, the solution is a good pragmatic choice. It's just interesting how our collective consciousness of expansive scientific fields can be so thoroughly purged when a new paradigm arises.

LLMs have completely overshadowed ML NLP methods from 10 years ago, and they themselves replaced decades statistical NLP work, which also replaced another few decades of symbolic grammar-based NLP work.

Progress is good, but it's important not to forget all those hard-earned lessons, it can sometimes be a real superpower to be able to leverage that old toolbox in modern contexts. In many ways, we had much more advanced methods in the 60s for solving this problem than what Harper is doing here by naively reinventing the wheel.

tough• 1 year ago

to someone who would like to study/learn that evolution, any good recs?

jasonjmcghee• 1 year ago

This skips over Bag of Words / N-Gram / TF-IDF and many other things, but paints a reasonable picture of the progression.

1. https://jalammar.github.io/illustrated-word2vec/

2. https://jalammar.github.io/visualizing-neural-machine-transl...

3. https://jalammar.github.io/illustrated-transformer/

4. https://jalammar.github.io/illustrated-bert/

5. https://jalammar.github.io/illustrated-gpt2/

And from there it's mostly work on improving optimization (both at training and inference time), training techniques (many stages), data (quality and modality), and scale.

---

There's also state space models, but don't believe they've gone mainstream yet.

https://newsletter.maartengrootendorst.com/p/a-visual-guide-...

And diffusion models - but I'm struggling to find a good resource so https://ml-gsai.github.io/LLaDA-demo/

---

All this being said- many tasks are solved very well using a linear model and tfidf. And are actually interpretable.

chilipepperhott4• 1 year ago

I'll admit it's something of a bold label, but there is truth in it.

Before our rule engine has a chance to touch the document, we run several pre-processing steps that imbue semantic meaning to the words it reads.

LLMs have completely overshadowed ML NLP methods from 10 years ago, and they themselves replaced decades statistical NLP work, which also replaced another few decades of symbolic grammar-based NLP work.

This is a drastic oversimplification. I'll admit that transformer-based approaches are indeed quite prevalent, but I do not believe that "LLMs" in the conventional sense are "replacing" a significant fraction of NLP research.

I appreciate your skepticism and attention to detail.

s1291• 1 year ago

Here's an article you might find interesting: https://www.quantamagazine.org/when-chatgpt-broke-an-entire-...

0xjunhao• 1 year ago

In a world of LLMs, it's great to see classic NLP works like Harper. Both definitely have their own use cases.

msravi• 1 year ago

Looks very good. Was looking to replace ltex (which is really slow), but for some reason the nvim-lspconfig filetype setting for harper doesn't seem to have (la)tex listed as a default, although markdown and typst are listed. Anyone knows why?

chilipepperhott4• 1 year ago

Harper maintainer here

We've had some contributors have a go at adding LaTeX support in the past, but they've yet to succeed with a truly polished option. The irregularity of LaTeX makes it somewhat difficult to parse.

We accept contributions, if anyone is interested in getting us across the finish line.

cchance• 1 year ago

Any chance to get it working in word? my wife would love to use it most likely

sdtransier• 1 year ago

Harper was acquired by Automattic in January 2025

https://automattic.com/2024/11/21/automattic-welcomes-harper...

novoreorx• 1 year ago

Seeing Harper as an implementation of natural language's LSP brings me great joy, as it proves an idea I've had for a long time—natural language and programming languages are interconnected. Many concepts and techniques from programming languages can also be applied to natural language, making our lives more convenient. The development of LLMs and vibe coding has further blurred the boundary between natural language and programming languages, offering similar insights.

loughnane• 1 year ago

Surprised coming into this that I don't see anyone mentioning vale[0]. I've been using it for ~4 years now and love it.

I use grammarly briefly when it came out and liked the idea. Admittedly it has more polish than vale for people writing in google docs, &c. Still, I stick with Vale. Is there any case for moving to Harper?

[0] https://vale.sh/

aDyslecticCrow2• 1 year ago

Looks interesting for linting and cleaning markdown documentation, but it doesn't seem like a very competent "spellcheck". I'll check it out... but it doesn't actually do the same thing as Grammarly or Harper.

WhyNotHugo• 1 year ago

Vale requires a lot of tweaking, and I’ve never been able to get a rule set with which I’m happy.

It’s missing a default rule set with rules that are generally okay without being too opinionated.

aDyslecticCrow2• 1 year ago

Harper is decent.

I've relied on Grammarly to spellcheck all my writing for a few years (dyslexia prevents me from seeing the errors even when reading it 10 times). However, I find its increasing focus on LLMs and its insistence on rewriting sentences in more verbose ways bothers me a lot. (It removes personality and makes human-written text read like AI text.)

So I've tried out alternatives, and Harper is the closest I've found at the moment... but i still feel like grammarly does a better job at the basic word suggestion.

Really, all I wish for is a spellcheck that can use the context of the sentence to suggest words. Most ordinary dictionary spellchecks can pick the wrong word because it's syntactically closer. They may replace "though" with "thought" because I wrote "thougt" when the sentence clearly indicates "though" is correct; and I see no difference visually between any of the three words.

Breza2• 1 year ago

What's wild is that OpenAI's earlier models were trained to guess the next word in a sentence. I wonder if GPT-2 would get "though" correct more often than the latest AI-assisted writing tools like Grammerly.

There are some areas where it seems like LLMs (or even SLMs) should be way more capable. For example, when I touch a word on my Kindle, I'd think Amazon would know how to pick the most relevant definition. Yet it just grabs the most common definition. For example, consider the proper definition of "toilet" in this passage: "He passed ten hours out of the twenty-four in Saville Row, either in sleeping or making his toilet."

aagha• 1 year ago

Have you tried Hemingway Editor?

yablak• 1 year ago

Any chance to make the obsidian plugin work in mobile/Android?

krick• 1 year ago

How big is English in "English grammar checker"? Is it plausible to add other languages to it, or the underlying framework is so English-specific that it doesn't make sense to even bother building something else than English grammar checker upon it?

punkbit• 1 year ago

I've been a grammarly paying customer for at least 8 years. Nice to have an alternative :)

DavideNL• 1 year ago

Interesting, curious to try this;

I wonder whether it will impact the performance (Firefox) and things will become noticeably slower...

Recently i noticed highlighting extensions in Firefox were slowing things down significantly, not just loading but also while scrolling up and down web pages.

SZJX• 1 year ago

I was wondering about grammar checking tools in the era of LLMs, especially for grammar checks beyond English, and Sapling https://sapling.ai seemed decent. Nobody seems to have mentioned it here?

stevenhubertron• 1 year ago

It says it's disabled on Outlook's web client and it's not clear why or how to enable. If I can't use this to proofread emails what is the point?

iwinux• 1 year ago

Remind me in 5 years when it gains enough hand-written rules to catch the most basic grammar errors LOL.

Harper – an open-source alternative to Grammarly

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