Open-source alternatives to Grammarly

3 alternatives, ranked by a published maintenance score computed from live GitHub signals (fetched 2026-09-04). We flag unmaintained projects on both sides — including Grammarly itself when the data says so.

About Grammarly: Proprietary SaaS; your text is processed on Grammarly's servers, a dealbreaker for confidential writing. It is closed-source, so the same public maintenance signals do not exist for it — we score only the alternatives below.

The alternatives

Harper

87 /100 actively maintained

Fast local-first grammar checker; runs entirely on your machine.

14,956 stars · last commit 2026-09-03 · latest release v2.9.1 (2026-09-01) · 882 open issues/PRs · Apache-2.0 · fetched 2026-09-04

How this 87/100 was computed

Last commit	yesterday	40/40
Latest release	3 days ago	25/25
Community size	GitHub stars	12/15
Open-issue trend	not enough history yet — needs snapshots 21+ days apart; neutral 10/20 awarded meanwhile	10/20
Total		87/100

Vale

87 /100 actively maintained

Command-line prose linter enforcing your own style guide.

6,075 stars · last commit 2026-09-02 · latest release v3.20.0 (2026-09-02) · 34 open issues/PRs · MIT · fetched 2026-09-04

How this 87/100 was computed

Last commit	2 days ago	40/40
Latest release	2 days ago	25/25
Community size	GitHub stars	12/15
Open-issue trend	not enough history yet — needs snapshots 21+ days apart; neutral 10/20 awarded meanwhile	10/20
Total		87/100

LanguageTool

81 /100 actively maintained

Grammar and style checker for 25+ languages; can run fully offline.

14,961 stars · last commit 2026-09-04 · latest release v6.8 (2026-05-05) · 2,145 open issues/PRs · LGPL-2.1 · fetched 2026-09-04

How this 81/100 was computed

Last commit	today	40/40
Latest release	4 months ago	19/25
Community size	GitHub stars	12/15
Open-issue trend	not enough history yet — needs snapshots 21+ days apart; neutral 10/20 awarded meanwhile	10/20
Total		81/100