Getting started

Setting up

• Open the invitation, pick the name you want to sign in with, and set a pass phrase of at least 12 characters.
• Your name is also your namespace, so choose one you are happy to see on the front of every link you make. It can be changed later, with a wait between changes, and the old one is never given to anybody else.
• Set up a six-digit code from an app on your phone. Keep the ten backup codes it shows you: there is no email address on file here, so those codes are the way back in if the phone goes.
• Add a passkey afterwards if the device supports one. It is one step instead of two, and a passkey that asks for a fingerprint or a PIN is already two factors on its own.
• The Appearance button (top right) also has Color vision: Protanopia, Deuteranopia and Tritanopia each swap the state colors, and the link color where it would clash, for a set tuned and tested for that type. Every state also has a word or a shape, so nothing depends on color alone. Like the theme, it is kept in this browser only.
• Appearance → Cursor: the pointer is drawn in your theme's colors. Tick Use the system cursor to keep your own, which also keeps your operating system's pointer size and color settings. High contrast, e-ink, Windows High Contrast and touch screens always use the system cursor.

Your first link

Paste a URL into Target URL on the dashboard and press Shorten. You get back https://geodzk.com/l/your-name/something, copied to the clipboard and ready to send. Leave Code empty for a short random one, or type your own.

curl -s -X POST https://geodzk.com/api/links \
  -H "X-API-Key: $GEODZK_KEY" -H 'Content-Type: application/json' \
  -d '{"url":"https://example.com/hello","code":"hello"}'

Codes, and why they never come back

• A code is one to sixty-four characters of A-Za-z0-9_-. Omit it and you get a random one of 5 characters.
• Delete a link and its code is retired, not freed. That address will never point at anything again, for you or for anybody else — because the old one may be on a poster somebody still has.
• So never delete a link to tidy up. Retarget it instead, or let it expire.
• If you want a retired code, you can ask the operator to release it, and they can. Nobody else can take it in the meantime.
• The bare space at https://geodzk.com/l/code belongs to the operator. Short, memorable top-level codes are held from the start so they stay available for the service's own use rather than going to whoever asked first.

What a link can be told to do

Channels are the one way to learn where a link's visits come from without learning anything about the visitors. Register tags with PUT /api/links/{code}/channels — poster, sheet, newsletter — and put one in the address you hand out: …/l/alice/party?via=poster. Each visit is counted against the tag. Nothing is read from the visitor; the tag names the poster, never the scanner. A tag nobody registered counts nothing, so a stranger cannot invent one. /print/l/{code}?via=poster puts the tag into the printed QR so a whole print run is counted as one channel.

When a link is followed is kept as 168 counters — weekday × hour, UTC — bumped at the click; no timestamp is written and the click's own second goes no further than that statement. GET /api/links/{code}/when releases them only above thresholds: nothing at all under 20 visits, and any cell under 3 as few rather than a number, because a cell of one is a person when you know who you handed the link to. The dashboard draws it as the field's own nodes. Beside it, readings: what those counters can say in a line each — quiet since, weekday share, busiest hours, how each printed tag did, refusals on a capped link — arithmetic under the same thresholds, nothing stored to produce it. ?further=1 computes the guesses (the crowd's time zone, which tag is ahead as ranges, next week from the average) only when asked; each refuses below its own floor and says in words that it is about everyone at once and never anyone.

What a visitor sees when a link does not work

None of these say whether a code ever existed, who owned it, or why it stopped. The recipient's next step is the same in every case, which is to go back to whoever sent it.

Your ceilings

Every account has a quota, and the dashboard shows where you are against it. Nought means no limit, never none allowed.