# Build brief — a focused alternative to LanguageTool

> **Verdict:** Yes, for personal use · **Buildability:** 90/100 · **Category:** AI Writing
> **Source:** https://www.canitbevibecoded.com/languagetool
> Independent editorial assessment from Can It Be Vibe Coded? Not affiliated with, endorsed by, or derived from LanguageTool. Verify current pricing and capabilities before acting.

## Context

**LanguageTool** — Grammar and style checker with browser extensions and premium suggestions. It currently costs $19.9/mo.

Because the core engine is open source, a technical user can run the grammar checker locally or self-host the server for many use cases.

This brief describes a focused, single-operator replacement for the part of LanguageTool that is genuinely reproducible. It is deliberately narrower than the product it replaces, and it says so in writing. Build the useful core; do not pretend to have rebuilt the rest.

## What you are building

Run LanguageTool locally/self-hosted, connect it to an editor/browser workflow, and optionally add LLM rewrites.

- Wrap a model API in a focused drafting, revision, and export workflow.
- A responsive interface with real empty, loading, success, and error states.

## Requirements

### Functional

- Java runtime or Docker.
- Local/server install.
- Browser/editor integration.

### Data and integrations

- Optional LLM API.

Each of these needs a real account, credential, or quota. Set them up before writing feature code.

### Non-functional

- Accessibility: semantic markup, labelled controls, visible focus, and reduced-motion support.
- Security: server-side secrets, validated input, and no credentials in the client bundle.
- Reliability: retries with backoff on external calls, and a clear failure state when a provider is down.
- Portability: the operator can export their data and leave without losing it.

## Implementation brief

Build me a local grammar checker to replace LanguageTool Premium. Requirements:

- Do not reimplement the checker: run the open-source LanguageTool server locally
  (the Java 17 jar, skip Docker) on localhost:8081, started by a wrapper script.
- A CLI: `check file.md` prints issues with line numbers, grouped by rule category,
  and exits nonzero when errors are found so it works as a pre-commit hook.
- A tiny web page on localhost:4860 (Express, one textarea): paste text, see
  underlined issues with suggested fixes, click a suggestion to apply it.
- Optional LLM rewrite button: send a paragraph plus the LanguageTool findings to
  Claude or GPT (key in .env) and show the corrected version as a diff.
- Personal dictionary in a plain words.txt that the server loads, so my names and
  jargon stop flagging.
- A setup script that downloads the LanguageTool release zip, and optionally the
  n-gram data. Warn in the README: the n-gram files are about 8 GB but catch far
  more real errors.
- Everything runs locally and works offline except the optional LLM call. No
  accounts, no telemetry.
- Out of scope: browser extensions and the premium-only rules. The open rule set is
  what we get.
- README: Java install, memory flags for the server, and wiring the CLI into git
  hooks.

## Delivery standard

- Inspect the repository first, then write a short implementation plan before writing code.
- Deliver the smallest complete end-to-end workflow first; every primary control must work against persisted data.
- Use real validation and storage; never substitute fake dashboards, decorative controls, hard-coded success states, or mock integrations.
- Include responsive layouts plus genuine empty, loading, success, validation, and failure states.
- Keep secrets server-side in environment variables, provide .env.example, and never commit credentials or user data.
- Add structured logs around every external call and return actionable errors without leaking sensitive details.
- Write unit tests for the core logic and one automated test of the main user journey.
- Finish with a README covering setup, architecture, data location, backups, tests, deployment, and known limitations.

## Acceptance criteria

- [ ] A clean install starts the app using only the README and .env.example.
- [ ] The primary journey works from first visit through saved result, reload, edit, export, and deletion where applicable.
- [ ] Invalid input, missing configuration, provider failure, and an empty database each have a usable state.
- [ ] The interface works at 390px and 1440px, is keyboard navigable, and shows visible focus on every control.
- [ ] Tests, type checking, linting, and a production build all pass with no ignored failures.
- [ ] No part of the interface implies a live integration, security guarantee, or scale capability that was not actually built and verified.

## Non-goals

Do not build these, and do not claim to have replaced them:

- Premium rule set.
- Hosted server convenience.
- Browser extension premium flows.
- Team/admin options.
- The last 20 percent is sync, migration fidelity, speed, and edge cases.

## What you still own after launch

- Secure credentials, rotate secrets, and handle provider rate limits.
- Run migrations, backups, restores, and dependency updates.
- Test the critical journey after every model, API, or hosting change.
- Monitor failures and fix the edge cases a first prompt will miss.

## Risk

**Manageable.** A personal version is realistic if you test the critical journey and keep reliable backups.

Editorial confidence in this assessment: high. No independent one-shot implementation is linked yet.

## Prior art

Working open-source software you can read, fork, or borrow from before starting:

- [LanguageTool](https://github.com/languagetool-org/languagetool) — The product's own open-source core engine

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Generated by [Can It Be Vibe Coded?](https://www.canitbevibecoded.com) · Full report: https://www.canitbevibecoded.com/languagetool