GrammarBot
FreemiumGrammar checker API built for developers, fast, affordable text correction with simple REST endpoints and high free tier limits
What is GrammarBot?
GrammarBot is a grammar checker API targeted at developers who need to embed text correction into their own applications, chatbots, content management systems, forum platforms, e-learning tools, customer feedback forms, and AI writing apps. Unlike Grammarly, which focuses on end-user writing experiences, GrammarBot is API-only and does not ship with a browser extension or writing app. Developers send text to a REST endpoint, GrammarBot returns a JSON array of suggested corrections (grammar, spelling, punctuation, style) with offsets and replacement text, and the developer's app renders the suggestions however fits the UX. Pricing has moved away from the named monthly plans we listed in May 2026. GrammarBot Neural is now sold by usage through RapidAPI, and the vendor's own docs quote $0.02 per 1,000 characters below 3 million characters per month, $0.015 from 3 to 12 million, $0.01 from 12 to 30 million, and a custom quote above 30 million. GrammarBot's worked example puts 1,000 submissions of roughly 100 words each at about $10. The older first-generation API is still supported and still gives 500 requests per month at no cost once you hold an API key. For comparison, Grammarly API access is enterprise-only and costs dramatically more. GrammarBot is built on a combination of proprietary models and LanguageTool under the hood, supports English (US, UK, Canada, Australia), and caps a single Neural request at 5,000 characters (10,000 on the first-generation endpoint), so longer documents have to be split. Common use cases include adding grammar checking to no-code AI apps, moderating user-generated content, improving chatbot responses, and powering in-browser writing feedback in e-learning tools.
⚡ Quick Verdict
Developers integrating grammar checking into apps, chatbots, or content platforms without enterprise budgets
End users who want a polished writing app, use Grammarly instead
Usage-based, from $0.02 per 1,000 characters, billed through RapidAPI
Yes, 500 requests per month on the first-generation API with a key
Affordable API with high free tier limits and simple REST integration
No end-user app, API only
Bottom line: GrammarBot scores 4.2/5, The most developer-friendly grammar checking API for startups and indie apps that need to embed correction features.
Pricing
Plan structure changed. The named monthly tiers we listed in May 2026 (Personal $9, Business $29, Enterprise $99) are not on GrammarBot's site. The vendor now prices GrammarBot Neural by characters submitted, and access is sold through RapidAPI.
GrammarBot Neural, usage-based: $0.02 per 1,000 characters below 3 million characters per month, $0.015 per 1,000 characters from 3 to 12 million, $0.01 per 1,000 characters from 12 to 30 million, and a custom quote above 30 million. GrammarBot's own worked example prices 1,000 submissions of roughly 100 words each at about $10.
First-generation API, free tier: 500 requests per month at no cost with an API key, with paid options for higher volume. GrammarBot says this older endpoint stays supported alongside Neural.
Direct connection: for high-volume or privacy-sensitive applications, GrammarBot will let you connect to its servers directly and bypass RapidAPI. Terms are quoted on request.
Note: the individual RapidAPI plan tiers and the Neural free allowance sit behind RapidAPI's JavaScript-rendered pricing table, which we could not read, so we have not restated them here.
Key Features
- Simple REST API with JSON responses
- Grammar, spelling, punctuation, and style checking
- Up to 5,000 characters per Neural request, 10,000 on the first-generation API
- English support for US, UK, Canada, Australia
- 500 free requests per month on the first-generation API
- Optional auto-correction that returns corrected text directly
- Custom spelling dictionary filtering documented in vendor tutorials
- Direct server connection available for high-volume or privacy-sensitive apps
- RapidAPI analytics dashboard and browser-based request testing
- Vendor-claimed 99.99% uptime, with 90% of requests completing under one second
Pros & Cons
Pros
- Most affordable grammar API on the market
- Free tier covers prototyping at 500 requests per month
- Simple REST integration takes minutes
- No vendor lock-in, switch LanguageTool anytime
Cons
- API-only, no end-user app or extension
- English-focused, weaker on non-English languages
- Style suggestions less nuanced than Grammarly
FAQ
What is GrammarBot and who uses it?
GrammarBot is an API-only grammar checking service for developers who need to embed text correction into their own applications. Typical users include startups building AI writing apps, e-learning platforms adding student feedback, chatbot developers improving response quality, and content management systems checking user submissions. GrammarBot does not target end users directly, it is infrastructure that other apps build on top of.
Is GrammarBot's free tier actually free?
Yes, but the allowance is smaller than we reported in May 2026. GrammarBot's own documentation states that the first-generation API gives 500 requests per month at no cost once you hold an API key, not 250 requests per day. That is still enough for a side project or a hobby app, though not for a launched product with real traffic. Beyond the free allowance, GrammarBot Neural is billed by characters submitted through RapidAPI rather than by a fixed monthly plan.
GrammarBot vs Grammarly API, which should developers pick?
For most developers, GrammarBot is the only practical choice. Grammarly does not offer self-serve API access, it is enterprise-only with pricing typically in the thousands per month and contract negotiations. GrammarBot provides immediate self-serve API access through RapidAPI, billed by usage from $0.02 per 1,000 characters, so a small integration can cost a few dollars a month. Grammarly's suggestions are slightly more nuanced, but the access difference is enormous. For any indie or startup project, GrammarBot is the practical pick.
Does GrammarBot support non-English languages?
GrammarBot officially supports English in US, UK, Canadian, and Australian variants. Some non-English languages work on a best-effort basis via the underlying LanguageTool engine, but they are not officially supported or guaranteed. If you need serious multilingual grammar checking, LanguageTool directly or a paid multilingual service like DeepL Write is a better fit.
Can I use GrammarBot in a commercial product?
GrammarBot's terms of use grant a limited, non-exclusive, non-transferable license to access and use the website and API, and the product is marketed to developers embedding it in their own applications. The terms do not spell out a separate free-tier commercial restriction, but they also do not contain an explicit commercial-use grant, so treat this as unconfirmed and email info@grammarbot.io before shipping a paid product on the free allowance. The practical constraint is volume: 500 free requests per month on the first-generation API will not carry a high-traffic commercial app, and Neural usage is metered per character.
How accurate is GrammarBot compared to Grammarly?
GrammarBot catches roughly 85-90% of what Grammarly catches for basic grammar, spelling, and punctuation. Where GrammarBot trails is nuanced style suggestions, tone, clarity, engagement, which Grammarly's proprietary models have been refined on for years. For core correction (is this sentence grammatically correct?), GrammarBot is sufficient for most apps. For writing polish, Grammarly remains the gold standard.
📋 Good to know
Signup runs through RapidAPI (linked from grammarbot.io) or the console at console.grammarbot.io. Grab an API key, then POST your text to the REST endpoint.
API requests processed in transit. For high-volume or privacy-sensitive applications GrammarBot offers a direct connection to its servers that bypasses RapidAPI, quoted on request. We could not find a published data retention policy for the API.
Move to metered GrammarBot Neural once you outgrow the 500 free monthly requests. Volume discounts kick in at 3 million and 12 million characters per month. Ask about a direct connection above 30 million.
Very low for developers familiar with REST APIs. Integration typically takes under an hour.
