Harper vs Vale
Self-host pick — both replace Grammarly (Writing assistant / grammar + style checker).
Both Harper and Vale self-host as a replacement for Grammarly (Writing assistant / grammar + style checker). Pick Harper if you want a Apache-licensed codebase (Apache-2.0); pick Vale for MIT (MIT). Both run in roughly the same cost bracket — $0 — harper runs locally (lsp) or in-browser (wasm) by default; no server required for personal use vs $0 — local binary; ci cost only if you run it in pipelines.
| Harperopen-source | Valeopen-source | |
|---|---|---|
| License | Apache-2.0 | MIT |
| Setup time | 5min — Rust binary, also runs as a VSCode extension and a browser extension | 10min — single Go binary + a styles directory |
| Monthly cost | $0 — Harper runs locally (LSP) or in-browser (WASM) by default; no server required for personal use. | $0 — local binary; CI cost only if you run it in pipelines. |
| GitHub | Automattic/harper | errata-ai/vale |
| Replaces | Grammarly | Grammarly |
Good fit for
Harper
Devs who want grammar/style checking that runs fully on-device with low latency and zero data leaving the box.
Weak at:Younger project — fewer rules than LanguageTool; English-only at the moment.
Vale
Documentation teams and devs who want enforceable, repo-checked-in style guides — turn 'use active voice' into a CI check.
Weak at:Not for casual prose — wrong shape for in-browser corrections; you write rules, not get sentences rewritten.
In a terminal? npx -y github:SolvoHQ/os-alt-cli grammarly prints Grammarly's self-host options including both —
how the CLI works →
FAQ
Which is easier to self-host, Harper or Vale?
Harper: 5min — Rust binary, also runs as a VSCode extension and a browser extension. Vale: 10min — single Go binary + a styles directory.
What does each cost to run?
Harper: $0 — Harper runs locally (LSP) or in-browser (WASM) by default; no server required for personal use.. Vale: $0 — local binary; CI cost only if you run it in pipelines.. Both projects are free and open source.
Do Harper and Vale replace the same SaaS?
Yes — both are open-source alternatives to Grammarly.