DeepFeather
中文

REPLACEMENT BRIEF

ai writing

Can AI replace Grammarly?

EDITORIAL ANSWERKINDACatalog estimate

Run text through LanguageTool plus an LLM rewrite/tone checker, expose a browser extension or local editor.

Build the personal version →

AT A GLANCE

price
$30/mo
listed annual price
$360/yr
replaceable scope
Run text through LanguageTool plus an LLM rewrite/tone checker, expose a browser extension or local editor.
build time
multi-day

what AI can build

Run text through LanguageTool plus an LLM rewrite/tone checker, expose a browser extension or local editor.

You can build grammar checks and rewrites, but Grammarly's moat is cross-app extensions, inline UX, enterprise controls, writing telemetry, and long-running language quality.

Editorial catalog estimate · not a completed build

The honest tradeoff

why people still pay

what you lose

inline suggestions everywhere

document/email integrations

tone/brand controls

enterprise admin

polished false-positive handling

Start with existing software

prior art · use these instead of building, if you'd rather

LanguageToolOpen-source grammar and style checker and the primary Grammarly-like prior art.↗

EVIDENCE LEDGER

What this page can prove

The verdict judges replaceability. The evidence level records what DeepFeather actually checked.

Read the methodology →
evidence level
Catalog estimate

Editorial catalog estimate · not a completed build

replacement boundaryRun text through LanguageTool plus an LLM rewrite/tone checker, expose a browser extension or local editor.

known limits · inline suggestions everywhere; document/email integrations

editorial reviewreviewed
Build promptcatalog estimate

the prompt

Catalog estimate
Build me a personal writing checker to replace Grammarly. Requirements:

- Grammar engine: LanguageTool running locally via its official Docker image;
  grammar checks never leave my machine.
- A local web page (Node + Express, binds to localhost): paste text, see
  LanguageTool issues underlined with hover explanations, click a suggestion
  to apply it.
- An LLM rewrite pane (key in .env) with three buttons: tighten, friendlier,
  formal. Show a diff against my original before I accept anything.
- A personal dictionary file (dictionary.txt) of names and jargon to never
  flag, passed to LanguageTool on every check.
- CLI mode: `check <file.md>` prints issues with line numbers, exits nonzero
  if any, so it can run as a git pre-commit hook on docs.
- Everything local except the optional LLM call; no accounts, no telemetry.
- Out of scope: a browser extension and inline suggestions inside Gmail,
  Docs, or Slack. This is a destination I paste into, that is the honest
  trade against Grammarly.
- README: Docker setup for LanguageTool, the roughly 1 GB of RAM it wants,
  and where the LLM key goes.
Copy or open in an agent

The prompt stays readable first. Choose a launch option when you are ready.

$ open in your agent (prompt prefilled, you press enter) or copy it raw · improve it via PR

BUILD FEEDBACK

Did you try this build?

Report the outcome. Submissions enter a manual evidence queue and never auto-upgrade the verdict.

LanguageTool
$19.90/mo · ai writingYESCanva
$18/mo · designKINDAFigma
$20/mo · designNOT REALLY

questions

Can AI replace Grammarly?

Possibly for a narrower core workflow, but this catalog judgment is not a verified build. Expected gaps include: inline suggestions everywhere, document/email integrations. Validate the prompt against your own acceptance criteria before committing.

How much does Grammarly cost?

Grammarly is listed at about $30/month (Pro, checked 2026-07-30), or $360 per year. This is a pricing reference, not evidence of a completed replacement or realized savings.

What do I lose by replacing Grammarly?

Honestly: inline suggestions everywhere; document/email integrations; tone/brand controls; enterprise admin; polished false-positive handling. If any of those are load-bearing for you, keep paying.

Is there an open-source alternative to Grammarly?

Yes — LanguageTool (Open-source grammar and style checker and the primary Grammarly-like prior art.). Using prior art is also a valid exit; the prompt is for when you want it exactly your way.