c15t
Open-source consent banner for GDPR/DSGVO with full developer control
AI Summary
c15t is an open-source consent management tool that runs entirely in the frontend and manages cookie banners as well as script loading. It offers maximum performance (89ms), full customizability and works with all common frameworks like React, Vue, Next.js and Svelte. Developers retain complete control over design and functionality.
✓ Pros
- + Extremely performant (89ms vs. 445-709ms for competitors) and minimal bundle size
- + Open source with full customizability of design and functionality
- + Framework-agnostic and works with React, Vue, Svelte, Next.js and more
✗ Cons
- − Relatively new (v2.0), therefore possibly less established than commercial solutions
- − Requires technical know-how for individual customizations
Use Cases
- → Implement GDPR/DSGVO-compliant cookie banners for websites and web apps
- → Set up performance-optimized consent management for marketing websites
- → Deliver geo-location-based consent banners with different languages
- → Load tracking scripts (Google Analytics, Meta Pixel etc.) in compliance with regulations
Who is it for?
Web developers and teams looking for a performant, customizable GDPR solution with full control instead of bloated SaaS alternatives
Tags
What is c15t?
c15t (pronounced "consent") is an open-source consent management tool that runs entirely in the frontend. It displays cookie banners, manages user consent, and controls the loading of third-party scripts such as Google Analytics or Meta Pixel. Everything works without a central SaaS backend layer that developers can neither control nor customise.
The name is a numeronym: "c" plus 15 letters plus "t". Version 2.0 is the current major release. The project is publicly available on GitHub.
Core features
- Cookie banner with script gate: Tracking scripts are only loaded once the user has given consent. This prevents unauthorised data transmission before consent is collected.
- Performance advantage: c15t reports a load time of 89ms, compared with 445 to 709ms for commercial alternatives. The bundle size is kept correspondingly small.
- Framework support: Native integrations for React, Vue, Next.js and Svelte are included.
- Geo-based rendering: Banners can be served based on the user's location and in multiple languages, addressing the different legal requirements across regions.
- Full customisability: Design and behaviour can be configured without any dependency on an external dashboard.
Who is c15t for?
c15t is aimed at developers who want to keep consent management under their own control. Teams running a marketing site with many third-party scripts, and unwilling to accept a performance hit from a bloated consent widget, will find a clear approach here.
For teams without strong frontend expertise, setup is more involved. Custom modifications require knowledge of the relevant framework. Anyone looking for a pre-configured solution with a GUI dashboard and legal guidance will not find that in c15t.
Context & alternatives
c15t belongs to the category of consent management platforms (CMP), though it does not compete directly with traditional SaaS providers such as Cookiebot, OneTrust or Usercentrics. Those services offer managed interfaces, automated cookie scanning and legal templates, but require a monthly subscription and offer little control over performance and markup.
A closer point of comparison is Klaro, which is also open source and self-hosted. c15t sets itself apart through its explicit performance focus and framework-native integrations, rather than a plain JavaScript snippet.
Anyone who wants GDPR compliance without a SaaS dependency, and is willing to maintain and extend the banner themselves, gets a technically controllable foundation with c15t.
