Harper
Open-source · self-hostable · replaces 1 SaaS tool on os-alt
Automattic/harper · alive · ★ 10.5k · last commit today · 537 open issues
License: Apache-2.0
Good fit for 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.
In a terminal? npx -y github:SolvoHQ/os-alt-cli grammarly prints
the Grammarly comparison table including Harper.
how the CLI works →
Replaces these SaaS
- Grammarly · Writing assistant / grammar + style checker
Install the Harper VSCode / Obsidian / Zed plugin or the browser extension. There is no migration data in Grammarly to bring over — switch the extension and point your IDE at the Harper LSP. For self-hosted as a server, run `harper-ls --stdio` behind any LSP-aware proxy or run the WASM bundle in your own page.
README badges for the SaaS this replaces
Maintainers and forks: drop a badge in your README to link readers from the SaaS-comparison page back to your repo.
FAQ
Is Harper actively maintained?
Yes — last commit today. The repository is alive (commit activity within the past 90 days).
What does Harper cost to self-host?
Harper is free and open source under Apache-2.0. Typical self-host VPS cost: $0 — Harper runs locally (LSP) or in-browser (WASM) by default; no server required for personal use.
Which SaaS does Harper replace?
Harper is listed as an open-source self-host alternative to: Grammarly.