Free URL Shortener PHP Script with QR Codes

LinkZip is a Bitly-style URL shortener that lives in a single PHP file on your own domain. Paste a long link, get a short code plus a scannable QR code, and watch click counts in the admin panel.

Links are stored in a JSON file with proper file locking — no database to set up. Short codes skip look-alike characters (0/O, 1/l/I) so they survive being read out loud. Only http(s) destinations are accepted, and an optional .htaccess snippet (included in the README) gives you pretty URLs like yoursite.com/l/Ab3xYz.

1. Upload linkzip.php to your web space (e.g. public_html/l/).
2. Open it in your browser once — storage bootstraps and locks itself down.
3. Open linkzip.php?a=admin, generate your admin password hash with the built-in generator, paste it into the CONFIG block.
Optional: add the 3-line .htaccess from the README for pretty short URLs.

Paste this prompt into Claude to build this exact product:

Build a complete, production-quality single-file PHP application called LinkZip: a self-hosted URL shortener with QR codes.

Core flow: paste a long URL, get a short link (?c=CODE) plus a scannable QR code; visiting the short link 302-redirects to the destination and increments a click counter.

Hard requirements:

- One PHP file, PHP 8.1+, no database: links live in one JSON file, read-modify-write wrapped in flock (shared lock for reads, exclusive for writes).

- CONFIG constants: DEMO_MODE, CODE_LENGTH, MAX_URL_LENGTH, ADMIN_PASSWORD_HASH, APP_NAME.

- Validation: only http/https destinations, URL length capped, parse_url-based checks. Short codes are generated from an alphabet WITHOUT look-alike characters (no 0/O, 1/l/I) and collision-checked.

- QR: render client-side with the qrcodejs library from cdnjs (the only external asset, browser-side only — the server must not call any external service).

- Admin panel at ?a=admin: session login (password_hash + sleep(1) on failure), KPIs (link count, total clicks, code length), table of links (code, destination, clicks, created date) with per-row delete, CSRF everywhere, first-run hash generator as in the SendZip pattern.

- Demo mode: UI visible, creating links and admin login disabled with a friendly message + top banner.

- Storage folder self-bootstraps with a deny-all .htaccess. Clean dependency-free CSS, dark mode, copy button next to the short link.

Also write a README.md: requirements, 3-step install, a rewrite-rule snippet for pretty URLs (yoursite.com/l/Ab3xYz), security design, and honest limits (JSON scale, abuse note for public shorteners).

What happened when we ran it: Claude (claude-fable-5) produced the complete file in one pass. Syntax check and the functional tests passed on the first attempt. Your result will differ slightly on every run — that's normal; the spec above pins the behavior, not the exact code.

Note: the download on this page ships with DEMO_MODE = false — no demo restrictions. The prompt is for reproducing (or remixing) the build yourself with your own Claude subscription.