Relay · self-hosted link shortener

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A link shortener you fully own, running on the Cloudflare edge. A single Worker is both the redirect engine and the admin API, data lives in D1, and the admin dashboard is a single index.html (zero build, zero external dependencies).

Just open index.html in a browser to try it — it defaults to DEMO mode (fake data; create / edit / view analytics). Follow the steps below to go live for real in about 10 minutes.

Core idea: a short link isn't just "making a URL shorter" — it's a relay station you control. Every link passes through your station before redirecting out, so you can track performance, change destinations any time, and build a retargeting audience.

Why Relay?

Link shorteners are everywhere — so why self-host one? Because with a free link shortener, you're really paying with your own traffic data — and the features you actually want are usually locked behind a paywall. Relay puts that relay station back in your own hands:

Change the destination without changing the link Campaign rotates, landing page moves, a partner drops out — repoint the link from the dashboard any time. Links you've already posted or printed never need to change.

See which channel actually drives clicks Add a suffix to the same link to split sources: /spring/ig, /spring/threads, /spring/edm each count separately. Which platform, which creator works — read it off the numbers instead of guessing.

Know which channel actually converts Clicks are only half the story. Report signups / sales back with a cookieless /track postback and the dashboard shows conversions and conversion rate per /suffix — so you see which channel drives results, not just traffic. No cookies, no cross-site identity: the thing cookie-based tools can't do privacy-first.

Turn clickers into your retargeting audience Links can carry FB Pixel / GA4 / GTM — visitors are written into your retargeting list before they even reach the destination. Every click becomes an audience touchpoint instead of leaking away.

A/B test, and route by device or country Weighted split to see which variant converts; or send traffic to different destinations by device (iOS / Android) and by country (request.cf.country) — one link, the right landing page per audience.

Your data, 100% yours Links, clicks, and audience all go into your own Cloudflare D1. No third party reading your traffic, nobody moving features behind a paywall, no links dying because a service shut down.

Free, no limits, your domain Runs on your own Cloudflare free tier (100k redirects/day is plenty), no cap on the number of links, and you can attach your own short domain (go.yourbrand.com).

Who it's for

• Creators, marketers, and small teams running multiple platforms / accounts who want to know where attention and results come from
• People who value data ownership and don't want to be locked into — or priced up by — a SaaS
• Anyone who wants short-link infrastructure they fully own and can modify and extend

Who it's not for (straight talk)

• If you just shorten the occasional URL and don't care about data — a ready-made service like Bitly is less hassle
• If you don't want to touch a terminal at all — Relay needs a few wrangler commands (~10 min) to go live

Features

• Link redirect — edge redirects, low latency worldwide
• Change destination without changing the link — repoint a posted link any time from the dashboard
• Weighted A/B split — randomly send the same link to different versions by weight
• Device & geo routing — send iOS / Android and per-country (request.cf) traffic to different destinations
• /suffix source tracking — add a suffix (e.g. /spring/ig) to count sources separately and see which channel works
• Marketing pixel interstitial — FB Pixel / GA4 / GTM: clickers are added to your retargeting list before they reach the site
• Password protection, expiry, 301 / 302
• UTM builder, QR code
• Analytics — device / OS / referrer / country / hour / suffix / A-B variant
• No link cap, custom domain, data 100% in your own hands
• Cookieless conversion tracking — attribute signups/sales to links and channels via a /track postback, zero cookies
• Unique visitors — total clicks plus a privacy-preserving daily unique count (IP / UA never stored)
• CSV / JSON export — download your raw click data any time
• Optional edge cache & auto-retention — KV-cached redirects for scale; Cron-pruned old clicks

Files

relay/
├─ worker.js       redirect engine + admin API (deploys to Cloudflare Workers)
├─ schema.sql      D1 tables
├─ wrangler.toml   Worker config (committed; D1 auto-provisions, secrets stay out)
├─ index.html      single-file admin (drop on Cloudflare Pages, or open locally)
└─ README.md

Deploy

One-click: click the Deploy to Cloudflare button above — it forks the repo, provisions D1 (and KV if you enable it), and deploys. Then run the two commands below to load the schema and set your ADMIN_TOKEN.

Or step by step (~10 minutes):

0. Prerequisites

npm i -g wrangler
wrangler login

1. Create D1 and import the schema

wrangler d1 create relay
# Paste the returned database_id into wrangler.toml (uncomment the database_id line)

wrangler d1 execute relay --remote --file=./schema.sql        # cloud
# wrangler d1 execute relay --local  --file=./schema.sql       # local testing

2. Set the admin secret

wrangler secret put ADMIN_TOKEN
# Enter a long random string — this is your admin login key

3. Deploy the Worker

wrangler deploy
# You get a URL, e.g. https://relay.<your-subdomain>.workers.dev

4. Connect the dashboard

1. Open index.html in a browser (or drop it on Cloudflare Pages).
2. Go to Settings on the left and fill in:
   • Worker API URL: the URL from the previous step
   • Admin key: the ADMIN_TOKEN you set in step 2
3. Click Test connection — success means you're done. The key lives only in your browser's localStorage.

Custom short domain (optional)

1. Add your domain to Cloudflare (e.g. relay.to).
2. Uncomment the [[routes]] block at the bottom of wrangler.toml and set pattern.
3. wrangler deploy. Your short links are now https://relay.to/spring.

API (all require Authorization: Bearer <ADMIN_TOKEN>)

Public redirect: GET /:slug or GET /:slug/:suffix (suffix tracks the source, e.g. /spring/ig).

Conversion postback (public, no Bearer): POST /track or GET /track?slug=… — report a conversion for a slug / suffix (see Conversion tracking). Optionally gated by a CONVERSION_TOKEN.

Before going live

1. Destination URLs: on create/update, only http(s) is accepted, blocking abusable schemes like javascript: / data: at the source.
2. Abuse protection: a destination-domain blocklist is built in — set BLOCKLIST = "a.com,b.com" in wrangler.toml to block those domains (and subdomains), zero key needed. For more, set SAFEBROWSING_KEY (wrangler secret put) and links are checked against Google Safe Browsing on creation; leave it unset = disabled, still runs fine.
3. Timezone: dashboard stats (today's clicks / daily trend / hour heatmap) use TZ_OFFSET in wrangler.toml, default +8 (Taiwan). Change it to your timezone elsewhere.

The QR code is generated locally in the browser by the inlined qrcode-generator (MIT) — it hits no third-party endpoint, so your link targets never leak and you don't depend on an external service staying up.

Security notes

• The admin API requires a Bearer token throughout; the token is stored via wrangler secret, never committed.
• Link passwords are stored hashed as sha256(slug + ':' + password), never in plaintext.
• All D1 queries use bound prepared statements to avoid SQL injection.
• Destination URLs on the interstitial page are safely embedded via JSON.stringify / attribute escaping to avoid XSS.
• Destinations only allow http / https, blocking dangerous schemes like javascript: / data: at the source.
• The QR code is generated locally in the browser (inlined qrcode-generator), hitting no external endpoint.
• robots.txt defaults to Disallow: /, so short links aren't indexed by search engines.

Conversion tracking (cookieless)

Relay attributes conversions to links without a single cookie. When someone completes an action on your destination (signup, purchase…), your site reports it back — server-to-server, aggregate, no cross-site identity:

curl -X POST https://<your-relay>/track \
  -H 'content-type: application/json' \
  -d '{"slug":"spring","suffix":"ig","event":"signup"}'

Fields: slug (required), suffix (the channel/KOL tag), variant, event (e.g. signup/purchase), value (optional number). A GET /track?slug=… with query params also works (for navigator.sendBeacon / pixels).

The dashboard then shows conversions, conversion rate, and a clicks→conversions table per channel — so you see which /suffix actually converts, not just which gets traffic. That's the thing cookie-based tools can't do privacy-first.

Abuse protection (optional): set a CONVERSION_TOKEN secret (wrangler secret put CONVERSION_TOKEN) and send it as the X-Conversion-Token header (or token field) — recommended for server-side postbacks. Unset = open beacon (fine for trusted/internal use).

Content loop — which channel to double down on

tools/rank.mjs turns your click + conversion data into a ranked channel scoreboard, so you know which /suffix to push next — not just which gets traffic, but which actually converts.

# from a deployed Relay (per-link stats):
curl -s "https://<your-relay>/api/stats/1?days=30" -H "Authorization: Bearer $ADMIN_TOKEN" \
  | node tools/rank.mjs -

# or from an exported file / a hand-built {channels:[...]} JSON:
node tools/rank.mjs data.json

It ranks channels by a Wilson lower bound on conversion rate (so a lucky "1 click, 1 conversion = 100%" never beats a proven channel), flags high-traffic-but-low-conversion sources, and tells you where to lean in. Zero dependencies. See tools/sample.stats.json for the input shape.

Then tools/pick-formula.mjs recommends which social-post formula to write the next post in to maximize reach/CTR — ranked by real break-out-of-follower-bubble evidence, optionally chained to the scoreboard (--data=rank.json):

node tools/pick-formula.mjs --goal=reach        # which formula gets seen by new people
node tools/pick-formula.mjs --no-hype           # skip hype-heavy formulas

The 27-formula framework is in Traditional Chinese and is derived from Hao0321/claude-skill-social-post (MIT) — see tools/CREDITS.md.

Privacy

Relay is built to be privacy-friendly by default — it tracks link clicks, not people:

• No cookies, no tracking script. Clicks are counted server-side at redirect time; nothing runs in the visitor's browser and no cross-site identifier is set.
• No IP stored. Only a coarse country code (from Cloudflare's edge) is kept — never the raw IP address.
• No raw User-Agent stored. Only the derived device / OS / browser is kept; the full UA string (a fingerprinting vector) is discarded.
• Referrer reduced to its domain. Only the source host (e.g. google.com) is stored — never the full URL with its path or query string.
• Bots excluded. Link-preview crawlers (Facebook, Slack, Discord, Telegram, etc.) are still redirected so previews work, but aren't counted and don't fire your pixels — so your numbers are real human clicks.
• Honors opt-out (optional). Set RESPECT_DNT = "1" and visitors sending DNT / Sec-GPC are redirected without being recorded.
• Your data, your server. Everything lives in your own Cloudflare D1; nobody else can read it.

Marketing pixels (FB / GA4 / GTM) are opt-in per link — only links you attach a pixel to load one, and only for real human visitors.

Scaling & upgrading (optional)

• Edge cache — bind a KV namespace as LINKS_KV (see wrangler.toml) and redirects read from KV first, cutting D1 reads and latency at scale. Edits still take effect within CACHE_TTL (default 60s). Not bound = always read D1 (instant, current behavior).
• Auto-retention — set RETENTION_DAYS and enable the [triggers] cron; clicks older than N days are pruned daily. Unset = keep forever.

Upgrading from an earlier version? Run this once against your D1, then re-run schema.sql to add the new conversions table (it uses CREATE TABLE IF NOT EXISTS, so it won't touch existing tables):

ALTER TABLE clicks ADD COLUMN visitor_hash TEXT DEFAULT '';

Fresh installs already include it via schema.sql. Without it, click recording fails silently until the column is added.

Cost

Fully self-hosted, running on your own Cloudflare account — there's no central server, and the author doesn't pay for anyone. For most people it's $0:

• Workers free tier: 100k requests/day
• D1 free tier: 5GB storage, millions of row reads per day
• Pages (hosts the index.html admin): free

You only pay past the free tier, and you pay your own Cloudflare bill — nothing to do with the author or other users. Fork it, fill in your own database_id and ADMIN_TOKEN, and it's 100% yours.

Development

Pure node:test unit tests cover the redirect / privacy / parsing helpers — zero dependencies:

node --test

CI runs them on every push and PR (.github/workflows/ci.yml).

License

MIT © 2026

Free to use, modify, distribute, and sell — just keep the copyright notice. Forks, stars, and issues welcome.