QR Code Generator APIs: REST, SVG Endpoints, and Rate Limits

1. Three Approaches

* Client-side library: JavaScript runs in the browser, no server required, data stays local, and there is no rate limit. Suitable for most web apps. * Self-hosted library: Node.js, Python, Go, or Java library runs on your own server, giving full control over output format and size. * Third-party cloud API: A hosted endpoint that accepts parameters and returns an image or SVG. Quickest to integrate but adds a network hop, cost, and a dependency.

2. Common REST Pattern

``` GET /qr?data=https%3A%2F%2Fexample.com&ecl=M&size=300 ``` Typical parameters include `data` (URL-encoded payload), `ecl` (error correction level), `size` (pixels), and `format` (png or svg).

3. What to Watch

* Self-host or use a client library for sensitive payloads, because cloud APIs receive your data. * Cache generated images to avoid regenerating the same code. * Verify the output by scanning it programmatically in CI, not just visually.

4. SVG vs PNG from an API

SVG responses are resolution-independent. PNG responses need a size parameter; request at least 300 × 300 pixels and scale up for print.