Freedom251 › Plagiarism Detection Software
WINNOWR

What WINNOWR is
WINNOWR is an academic-integrity tool for finding possible web-source matches in student work and other long-form writing. It is designed to run CPU-first and gives reviewers evidence to examine, including index overlap, candidate source links, and suspicious passages highlighted in submitted text. Its matching process applies consistent text normalization and compact word-shingle fingerprints to identify candidate documents. Institutions can create an index from their own JSONL.zst corpus, typically containing URL and text fields, with title optional. The project also documents workflows based on FineWeb-Edu and Wikipedia. Text and files can be submitted through an HTTP API, which includes endpoints for submissions, reports, text, purging, and health checks. The documented system has an index builder, an API server, and a background worker. Its runtime uses SQLite, Cloudflare Queues, Cloudflare R2, and a local sharded disk index. Build and deployment instructions cover the API and worker, including plain Linux machines. WINNOWR is free and available as an API, web service, and self-hosted software. Longsight presents it for institutional plagiarism review and offers hosting and support. The project is still evolving, and source snippets or highlighted spans may not be available if a live page cannot be fetched or parsed. Its GNU AGPLv3 license requires modified deployed versions to make those modifications available under the same license.
Who it suits
WINNOWR suits institutions seeking a self-hostable academic-integrity system that identifies web-source candidates and provides evidence for review. It may also suit teams able to build and maintain a corpus and operate the documented API and worker.
What it does well
- Free to use.
- Accepts text and file submissions through an HTTP API.
- Reports include overlap, source URLs, and highlighted passages.
- Institutions can build indexes from their own corpus.
- Deployment instructions include plain Linux machines.
What to know first
- The project is still actively evolving.
- Source snippets and highlighted passages may be unavailable for some pages.
- Modified deployed versions must share modifications under GNU AGPLv3.
Limits
WINNOWR is free. Source-page snippets and highlighted spans are best-effort and can be unavailable when a live page cannot be fetched or parsed.
Getting started
- Open the project repository at https://github.com/LongsightGroup/winnowr.
- Build an index from a JSONL.zst corpus with URL and text fields; title is optional.
- Follow the repository's build and deployment instructions for the API server and background worker.
- Run the documented runtime with its SQLite, Cloudflare Queues, Cloudflare R2, and local index components.
- Submit text or files through the HTTP API and use its report and health endpoints.
Verdict
Choose WINNOWR if an institution wants free, API-based web-source matching with reviewable reports and the option to self-host. Look elsewhere if you need a mature, fixed product or guaranteed page snippets and highlighted evidence; the project is still developing and that enrichment is best-effort.
Questions
How much does WINNOWR cost?
It is free, with a free plan.
Can an institution host WINNOWR itself?
Yes. The project describes itself as self-hostable and provides deployment instructions, including for plain Linux machines.
What can the API accept?
The HTTP API accepts text or file submissions and provides submission, report, text, purge, and health endpoints.
What does a report contain?
Reports include index overlap, candidate source URLs, and highlighted suspicious spans. Snippets and highlighted spans may be unavailable if a live page cannot be fetched or parsed.
What license does WINNOWR use?
The repository uses GNU AGPLv3. Its network-use provision requires modified deployed versions to make those modifications available under the same license.
Facts from WINNOWR's own pages
- Architecture
- The documented runtime uses SQLite, Cloudflare Queues, Cloudflare R2, and a local sharded index on disk. · github.com, 4 Oct 2026
- Audience
- Longsight presents Winnowr as academic-integrity software for institutions, with a focus on plagiarism detection and reviewable evidence. · longsight.com, 4 Oct 2026
- Company history
- Longsight says Sam Ottenhoff and Scott Siddall founded the company in 2004. · longsight.com, 4 Oct 2026
- Corpus options
- Users can build an index from their own JSONL.zst corpus; the repository also describes FineWeb-Edu and Wikipedia workflows. · github.com, 4 Oct 2026
- Corpus support
- Users can build an index from their own JSONL.zst corpus, with url and text fields generally needed and title optional. · github.com, 8 Oct 2026
- Deployment
- The README describes building the Go binaries and running the API and worker on a Linux machine. · github.com, 8 Oct 2026
- Hosting and support
- Longsight says it can host and support its products, and that products with a self-hosted option include a path for institutions to run them. · longsight.com, 4 Oct 2026
- Integrations
- The production-style runtime uses SQLite, Cloudflare Queues, and Cloudflare R2. · github.com, 8 Oct 2026
- License
- The repository is licensed under GNU AGPLv3. · github.com, 8 Oct 2026
- Limitations
- The README says source-page snippets and highlighted spans are best-effort enrichment and may be unavailable when a live page cannot be fetched or parsed. · github.com, 8 Oct 2026
- Matching
- It normalizes text, creates word-shingle fingerprints, searches an index for overlap, and fetches likely source pages for evidence. · github.com, 8 Oct 2026
- Maturity
- The README describes WINNOWR as usable but still actively evolving, with documentation and packaging catching up. · github.com, 8 Oct 2026
- Purpose
- WINNOWR is a CPU-first web-source detection engine for student writing and other long-form text. · github.com, 8 Oct 2026
- Reports
- Reports include index overlap, source URLs, and highlighted suspicious spans. · github.com, 8 Oct 2026
- Runtime
- The repository describes three main binaries: an index builder, an API server, and a background worker. · github.com, 8 Oct 2026
- Self-hosting
- The project describes itself as understandable and self-hostable, with an on-disk index and local runtime configuration. · github.com, 8 Oct 2026
- Submission methods
- The HTTP API accepts text or file submissions and provides submission, report, purge, and health endpoints. · github.com, 4 Oct 2026
- Submissions
- The API accepts text and file submissions and provides submission, report, text, purge, and health endpoints. · github.com, 8 Oct 2026
Where WINNOWR stands on Freedom251
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