Writing and content decision
Trinka
A capable developer can build a useful, privacy-respecting grammar checker and offline desktop app (core loop) in about a week, but reproducing Trinka’s full offering—plagiarism databases, journal-finder, large commercial integrations, and enterprise certifications—requires data, licenses, and operations that make keeping the commercial service reasonable for many users.
Visit website↗Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need — the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship.
What a replacement has to do
- Accept user text or uploaded document, run grammar/style/consistency checks, return annotated suggestions and allow applying edits; support offline processing for sensitive documents.
What it still won’t have
- Proprietary plagiarism database and marketplace integrations
- Journal-finder and large-scale citation quality checks backed by paid publication indexes
- Enterprise compliance, certifications, and Trust Center claims without formal audits
- Polished commercial integrations (Word add-in, multi-browser plugin, SDKs) and support
What remains hard
- Compliance and regulation
Confidential Data Plan No data storage. No AI training.
First-year cost
Keep paying
Paying is—cheaper in year one.
On cash alone, building overtakes the subscription at 18 seats.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a minimal privacy-first grammar-check web app using React for the frontend, a Python FastAPI backend, and an open-source grammar engine (e.g., LanguageTool or transformer-based rule+model) for analysis. In scope: (1) web editor that accepts pasted text and uploads .docx/.tex, (2) backend endpoints that return inline suggestions with explanations and categories (grammar, style, consistency), (3) apply-suggestion logic that updates .docx/.tex while preserving formatting, (4) an Electron desktop package that runs the backend locally for offline processing, (5) secure deletion/no persistent storage by default, error handling, and unit + integration tests. Out of scope: building a commercial plagiarism marketplace, paid publication-index integrations, custom enterprise SLAs, and advanced journal-finder features.
How we checked
How the score was reached
- Partly verdict base52
- An open-source build was found+5
- 5 cited sources+3
- Price verified on pricing page+3
- 3/3 assessment runs agreed+4
- Hard moats found in the evidence-3
- Evidence score64
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time — so the same evidence always produces the same number.
How scoring works →Cited sources · 5
Every page the run actually retrieved.
- official productTrinka AI homepage
- official pricingConfidential Data Plan for Grammar Checker (pricing & features)
- official productFeatures
- open sourcelanguagetool-org/languagetool
- open sourceAutomattic/harper
Integrity checks
What held up, and what did not.
