LibreCaptcha
Build self-hosted, privacy-respecting CAPTCHA flows with the LibreCaptcha framework.
About LibreCaptcha
LibreCaptcha is an open source framework for developers who want to build their own CAPTCHAs and run them on a server they host. The framework provides the API for a CAPTCHA generator and handles the surrounding work, including an HTTP interface for serving CAPTCHAs, background workers that pre-compute CAPTCHAs and store them in a database, management of CAPTCHA secrets such as tokens and expected answers, and garbage collection of stale CAPTCHAs.
The project includes several sample generators, such as ShadowText, FilterCaptcha, RainDropsCaptcha, PoppingCharactersCaptcha, and LabelCaptcha. The project states that the framework is stable but that this is its first public release, so it recommends using it only for small to medium scale web apps. The sample CAPTCHAs have not yet been tested against bots or CAPTCHA crackers. A sandboxed plugin architecture is listed as TBD.
Key features
- HTTP interface for serving CAPTCHAs to clients
- Background workers that pre-compute CAPTCHAs and store them in a database
- Management of CAPTCHA secrets such as tokens and expected answers
- Unique token generated for each CAPTCHA image impression
- Garbage collection of stale CAPTCHAs
- Included sample generators, including filter-based and label-based CAPTCHAs
Best for: Developers who want to run their own CAPTCHA service for small to medium scale web applications and customize CAPTCHA types to suit their audience.
Good for
- Lets a site host its own CAPTCHA service instead of depending on a third-party provider.
- Developers can create CAPTCHAs with themes and looks that match their application.
- Sample generators are included, so a basic deployment can start without writing a generator.
Watch out for
- This is the first public release, and the project recommends use only at small to medium scale.
- The sample CAPTCHAs have not been tested against bots or CAPTCHA crackers.
- The sandboxed plugin architecture is listed as TBD.
LibreCaptcha at a glance
- Category
- Privacy & Security › Security Tools
- Type
- Open-source project
- Pricing
- Not confirmed. Check the site
- Open source
- Yes · Source code
- Language
- English
- Last checked
- Oct 6, 2026 · Online when checked
- Listed
- Oct 5, 2026
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LibreCaptcha FAQ
How can LibreCaptcha be started?
It can be run with a Java jar file or by building it with sbt, and the project recommends a Java 11+ runtime. It can also be run with Docker or docker-compose, and the project notes that the commands should work with podman if the docker.io registry is configured.
Is LibreCaptcha recommended for large-scale sites?
The project recommends using it only on small to medium scale web apps, since this is its first public release.
How are CAPTCHA types configured?
If no config.json file is present in the data folder, the app creates one. This file can be edited to change which CAPTCHAs are enabled and their difficulty settings.
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