Built a CAPTCHA alternative in C with PoW, JA4, and puzzle in complex mode
Captxa is a high-performance CAPTCHA server designed to combat bots using a proof-of-work challenge and a slider-puzzle challenge. It is built in C and can handle over 50,000 concurrent validations per second. The server features advanced security measures such as TLS fingerprinting and IP reputation filtering.
- ▪Captxa serves both simple and complex CAPTCHA challenges.
- ▪It is optimized for high concurrency and low latency.
- ▪The server requires a Debian Linux environment for deployment.
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Story provenance
Attribution is not the same as permission. This drawer separates discovery metadata, excerpts, WeSearch-generated summaries, reuse status, and whether the publisher receives the visit. Nothing here claims a legal grant the publisher has not made.
Record
| Original publisher | GitHub |
| Canonical URL | https://github.com/captxa/captxa-backend |
| Publication time | Wed, 20 May 2026 18:31:09 +0000 |
| Retrieval time | 2026-05-20T18:35:02.972Z |
| Last seen | 2026-05-20T18:35:02.972Z |
| Headline source | Publisher (no WeSearch rewrite) |
| Excerpt source | publisher body |
| Excerpt method | First ~120 words (~800 chars) of extracted publisher body, fair-use limited. |
| Summary | WeSearch · cerebras-chat (WeSearch summarizer) |
| Summary source text | contentText |
| Citation coverage | Summary is a WeSearch-generated derivative; primary citation is the original publisher URL. |
| Cluster | VYtJLtkAklnn |
| Cluster logic | Grouped by semantic title/content similarity across sources within a rolling window. Same-publisher template collisions are excluded from coverage comparison. |
| Ranking reason | Story pages are not engagement-ranked. Hub feeds use recency, with optional source-diversified chronological ordering (cap consecutive stories per source). No personalized ranking. |
| Publisher visit | Yes — open original |
| Substitutes article? | No — link-out required for full text |
Rights status (four layers)
WeSearch handling by dimension
| Indexing | May the item be indexed (stored, ranked, made findable)? | Allowed |
| Snippet | May a short excerpt of the publisher's text be shown? | Allowed |
| AI summary | May WeSearch generate its own short summary of the article? | Limited |
| Retrieval / RAG | May the content be exposed for third-party retrieval-augmented generation? | Not asserted |
| Model training | May the content be used to train AI models? | Not asserted |
| Commercial reuse | May the content be reused commercially? | Not permitted |
Basis: Derived from the published RSS/Atom feed. Contact: [email protected]. Reviewed: 2026-07-24.
Opening excerpt (first ~120 words) tap to expand
Captxa — High-Performance CAPTCHA Server Captxa is a production-grade, anti-bot CAPTCHA engine written in C. It serves both a lightweight proof-of-work challenge ("simple") and a full slider-puzzle challenge ("complex") with mouse/touch trajectory analysis, TLS fingerprinting (JA4), GeoIP correlation, and IP reputation filtering. Zero-heap-allocation hot path. Sub-millisecond puzzle generation. Designed for 50k+ concurrent validations per second per core. Recommended hosting: Debian Linux server. How It Works See the full technical deep-dive at captxa.com/how_it_works.
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Excerpt limited to ~120 words for fair-use compliance. The full article is at GitHub.