Puter.js (free calls to GPT / Claude)

Called directly from a frontend JS library — developers don't need to bring their own API Key, with zero-cost integration under a 'User-Pays' model

The official documentation doesn't disclose specific rate limits or usage caps — it only states that requests go through authentication and rate-limiting to prevent abuse. The mechanism works by having the Puter platform absorb the actual usage cost from the end user (rather than the developer footing the bill); developers integrating it don't need to manage keys or pre-fund an account. Primarily called via browser-side JS, though an npm package is also available; the vendor doesn't explicitly guarantee stability or a quota ceiling for direct server-side calls.

⚠️Well-suited to quickly wiring up models like GPT or Claude for frontend demos or vibe-coding scenarios. In actual use, end users may be prompted to log into a Puter account — it isn't entirely login-free for every visitor. Production stability and rate-limiting behavior need hands-on testing; the vendor doesn't offer an SLA.