Quickstart

Make a QR code (no key)Copy Anchor Link

Run this. It saves a PNG of a QR code that opens qrdx.dev:

curl "https://api.qrdx.dev/v1/qr?data=https://qrdx.dev&format=png" -o qr.png

That's a working API call. The URL itself is the image, so it also works straight in an <img> tag:

<img src="https://api.qrdx.dev/v1/qr?data=https://qrdx.dev&fg=111111&body=circle" alt="QR code for qrdx.dev" />

Change the colors, shapes, size and format with query parameters, or try them in the browser on the Render a QR code image page: its Try it panel sends the request and shows the image. Images don't count against any quota; the limit is 300 requests a minute per IP address.

Get an access tokenCopy Anchor Link

Everything else in the API acts on an account: create dynamic codes, change where they point, read their scans. Those requests carry an access token in the Authorization header.

1. Register an app. In Settings → Developers, choose New app. Give it a name, add the redirect URI http://localhost:8787/callback, and select the scopes codes:read, codes:write and profile:read. Copy the client ID and the client secret (the secret is shown once).

2. Sign in through it. Save this script as get-token.mjs. It runs the OAuth flow with PKCE against your own account and prints your tokens. It needs Node 18 or later and nothing else:

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   import { createHash, randomBytes } from "node:crypto";
   import { createServer } from "node:http";
   
   const clientId = process.env.QRDX_CLIENT_ID;
   const clientSecret = process.env.QRDX_CLIENT_SECRET;
   const redirectUri = "http://localhost:8787/callback";
   
   const verifier = randomBytes(32).toString("base64url");
   const challenge = createHash("sha256").update(verifier).digest("base64url");
   const state = randomBytes(16).toString("hex");
   
   const authorize = new URL("https://qrdx.dev/api/oauth/authorize");
   authorize.search = new URLSearchParams({
     response_type: "code",
     client_id: clientId,
     redirect_uri: redirectUri,
     scope: "codes:read codes:write profile:read",
     state,
     code_challenge: challenge,
     code_challenge_method: "S256",
   });
   console.log(`Open this URL and approve your app:\n\n${authorize}\n`);
   
   const server = createServer(async (req, res) => {
     const url = new URL(req.url, redirectUri);
     if (url.pathname !== "/callback") return res.writeHead(404).end();
     const code = url.searchParams.get("code");
     if (!code || url.searchParams.get("state") !== state) {
       res.writeHead(400).end(url.searchParams.get("error") ?? "Bad callback");
       return;
     }
     const response = await fetch("https://qrdx.dev/api/oauth/token", {
       method: "POST",
       body: new URLSearchParams({
         grant_type: "authorization_code",
         client_id: clientId,
         client_secret: clientSecret,
         code,
         redirect_uri: redirectUri,
         code_verifier: verifier,
       }),
     });
     const tokens = await response.json();
     res.end(response.ok ? "Done: back to your terminal." : "Failed: see your terminal.");
     server.close();
     console.log(tokens);
   });
   server.listen(8787);

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   QRDX_CLIENT_ID=... QRDX_CLIENT_SECRET=... node get-token.mjs

   Open the URL it prints, approve your app, and the terminal shows access_token and refresh_token.

3. Keep it handy. Export the access token for the next step:

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   export QRDX_TOKEN=...

Access tokens last one hour; the refresh token gets you a new one for 30 days (refreshing tokens). Requests made with a token act on your personal workspace and count against its daily quota (1,000 requests on Free).

Create a dynamic codeCopy Anchor Link

A dynamic code is a short link you can point somewhere else after it's printed:

curl -X POST https://api.qrdx.dev/v1/codes \
  -H "Authorization: Bearer $QRDX_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"destinationUrl": "https://example.com", "title": "My first code"}'

The response is 201 Created with the new code:

{
  "data": {
    "id": "cm5code0spring0menu00001",
    "slug": "aB3dE5f",
    "shortLink": "https://qrdx.dev/q/aB3dE5f",
    "destinationUrl": "https://example.com/",
    "title": "My first code",
    "status": "active",
    "scanCount": 0
  }
}

(Shortened: Create codes shows every field.) The QR code encodes shortLink. Render it with the image API from step 1, https://api.qrdx.dev/v1/qr?data=https://qrdx.dev/q/aB3dE5f, and print it.

Point it somewhere elseCopy Anchor Link

Change the destination at any time; the printed code keeps working:

curl -X PATCH https://api.qrdx.dev/v1/codes/$CODE_ID \
  -H "Authorization: Bearer $QRDX_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"destinationUrl": "https://example.com/new-page"}'

Scan the code once, then read its analytics with GET /v1/codes/$CODE_ID/scans (Get scan analytics).