Can I Code This?

Can I code Grammarly?

An LLM pass catches most of what Grammarly catches — you're already paying for one. What you can't easily rebuild is the everywhere-ness: the underlines living inside every text box you type into.

VIBE SCORE 72/100

how this is worked out

categorywriting
time to codea weekend
Borderline
their price$12/mo · $144/yr
last checked2026-08 · source ↗

Why CanICodeThis says Borderline

  • A "proofread this" hotkey that sends your clipboard through a model and pastes the fix back covers most real usage
  • You control the style rules: your dictionary, your tone, no upsell nags mid-sentence
  • For long-form work, a CLI or editor plugin reviewing whole files beats sentence-by-sentence nagging

What you give up building Grammarly yourself

  • Real-time inline underlining in arbitrary apps means browser extensions and OS-level accessibility APIs — a real project, not a weekend
  • Latency: their suggestions appear as you type; a hotkey flow is a beat slower
  • Team style-guide enforcement across a company

What you'd have to build

The parts this build actually needs, each rated on its own — the average is the Vibe Score above.

OS-level integration72

How to build your own Grammarly

Build a hotkey-triggered proofreader, not real-time inline underlining everywhere: 1. A global hotkey that sends your clipboard text through an LLM API and pastes the correction back — covers most real usage. 2. Your own style rules (a custom dictionary, a tone instruction in the prompt) — no upsell nags mid-sentence. 3. For long-form work, a CLI or editor plugin reviewing whole files beats sentence-by-sentence nagging. That's a real, useful proofreading tool. Out of scope: real-time inline underlining in arbitrary apps, which means browser extensions and OS-level accessibility APIs — a real project, not a weekend — and team style-guide enforcement across a company, a separate, organizational feature.

What it actually costs to build

Two real costs, not just "free": the AI agent's own usage, and hosting once it's running. Both are estimated from this app's own effort rating and component list — see the assumptions on the method page.

AI agent — with a subscription (Claude Pro/Max, Cursor, etc.)$0 marginal
AI agent — pay-per-use API, no subscription$43–$86 one-time
Hosting, once it's running$0/mo (free tier)
Domain name, if you want your own~$12/yr

Grammarly costs $12/mo. Even paying per-token with no subscription, and accounting for hosting, this build pays for itself in about 8 months.

Open source Grammarly alternatives

Don't feel like building it? These are already made, open-source, and free.

LanguageTool ↗Open-source grammar checker with a self-hostable server if you want it fully local.

Questions

Can I code Grammarly?

Borderline. An LLM pass catches most of what Grammarly catches — you're already paying for one. What you can't easily rebuild is the everywhere-ness: the underlines living inside every text box you type into.

How much does Grammarly cost?

Grammarly costs $12/mo (about $144/yr) as of 2026-08. That's what a working rebuild would save you.

What do I lose by building it myself?

Real-time inline underlining in arbitrary apps means browser extensions and OS-level accessibility APIs — a real project, not a weekend Latency: their suggestions appear as you type; a hotkey flow is a beat slower Team style-guide enforcement across a company

Is there a free alternative to Grammarly I don't have to build?

Yes — LanguageTool are open-source options worth trying before you build your own. Details are in the standard parts section on this page.

Similar products you could build

Closest matches on the register — ranked by the build parts they share with Grammarly, not just by category.

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