Editing & Proofreading

Two distinct jobs: grammar / spelling (sentence-level correctness) and style / voice (clarity, tone, house-style adherence). The FOSS world is unusually strong here — LanguageTool is self-hostable and matches Grammarly on most checks; Vale is the prose-linter every technical writer eventually adopts. For the AI-assisted-writing debate see writing-ai-assistants.

Self-hostable / OSS (the headline)

• ★ ★ LanguageTool — LGPL; free + paid Premium; self-hostable; supports 30+ languages; the FOSS Grammarly. Browser extensions, LibreOffice / Word integrations, VS Code / Vim / Neovim via ltex-ls. Free tier is generous; Premium adds nuance.
  • https://github.com/languagetool-org/languagetool
• ★ ★ Vale — MIT; free OSS CLI; the prose-linter for technical writers. Bring or build a style guide (Google, Microsoft, GitLab, Mailchimp, write-good, alex, proselint rule packs ship as "styles"). Integrates with VS Code, Vim, GitHub Actions, CI.
  • https://github.com/errata-ai/vale
  • Vale styles — Google, Microsoft, GitLab, Mailchimp, alex, proselint, write-good are all available as style packs.
• ★ proselint — BSD; free OSS Python; rule-based prose linter ("avoid 'literally'", "avoid 'utilize'"); fast as a pre-commit hook.
  • https://github.com/amperser/proselint
• ★ write-good — MIT; free OSS Node CLI; classic "weasel word" detector.
  • https://github.com/btford/write-good
• alex — MIT; free OSS; flags insensitive / racist / ableist language; pairs well with Vale.
• textlint — MIT; free OSS; pluggable text linter; the JS ecosystem's Vale.

Hosted (paid + free) editing assistants

• Grammarly — paid subscription + free; the consumer default; browser-everywhere, Word add-in, Mac / Win apps. Premium adds tone, style suggestions. Cloud-only — your prose hits their servers.
• ProWritingAid — paid + free Lite; deeper than Grammarly on style reports (overused words, sentence variety, pacing); Word / Scrivener / browser; paid one-time lifetime sometimes available.
• ★ Hemingway Editor — paid; $20 one-time (desktop app); also free web. Clarity scoring (grade level), highlights long sentences, passive voice, adverbs. ★ for the fast clarity pass; doesn't replace a real edit.
  • https://hemingwayapp.com/

Apple-flavoured

• Apple Writing Tools (Apple Intelligence) — free; built into macOS Sequoia + iOS 18+ rolling out 2024-26; proofread, rewrite, summarize across any text field. Privacy story is good (on-device + Private Cloud Compute); coverage is improving but not as deep as ProWritingAid yet.
• PerfectIt — paid; Win / Mac; ★ for ★ professional copy-editors; consistency checking (US / UK spelling, hyphenation, capitalization style); pairs with the Chicago Manual of Style.
• Antidote — paid; Mac / Win / web; ★ for French + English users; the gold standard for French grammar; great English module.

Style guides as Vale packs

• Chicago Manual of Style (CMOS) — community Vale rule pack, partial.
• AP Style — community Vale pack.
• Microsoft Writing Style Guide — official Vale pack.
• Google developer-doc style — official Vale pack.
• GitLab handbook style — public Vale pack.
• Mailchimp / Buffer / 18F — public Vale packs; copy from these to bootstrap a house style.

Read-aloud (catch errors with your ears)

• See writing-text-to-speech-editing — Apple Speak Selection, Word Read Aloud, NaturalReader.

Working with human editors

• See writing-collaboration-track-changes for track-changes / Google Docs / Reedsy Editor.
• See writing-self-publishing-kdp for finding pro editors via Reedsy / EFA.

Pick this if…

• Free + self-hostable + multi-language: LanguageTool.
• Tech writer / docs team: Vale + a style pack + CI.
• Cheap clarity pass: Hemingway Editor ($20).
• Browser-everywhere consumer tool: Grammarly.
• Deep style reports: ProWritingAid.
• Pro copy-editor consistency: PerfectIt.
• French + English author: Antidote.
• Pre-commit hook for blogs: proselint or write-good.