SendURL Slug Rules: Length, Characters and Case

The slug is the part of a short link after the domain: in snu.to/spring-sale, it's spring-sale. It's the only part of a SendURL link you choose, and once a link exists it never changes. This post covers the two kinds of slug, the rules for custom ones, and how to pick a good one. Both kinds are available on every plan.

Random slugs

If you don't need a particular slug, SendURL makes one up from letters, upper and lower case, and digits:

• In the console, the Create link form starts with a random six-character slug, such as snu.to/aZ3k9Q. Choose Regenerate slug for a different one.
• Through the API, leaving out slug gives a random five-character one, such as snu.to/x7Kp2.
• Guest links from the home page also get five characters.

With 62 possible characters in each position, there are about 916 million five-character slugs and nearly 57 billion six-character ones, so random slugs stay short and almost never collide. If one ever does, you're asked to try again.

Random slugs are the right choice when nobody will type or read the link: links in emails, posts and chat messages that people tap, and QR codes, where shorter slugs also mean simpler codes.

Custom slugs

A custom slug is one you type yourself. In the console, switch Short link slug from Random to Custom and type it. The rules:

• 1 to 32 characters
• Letters a to z and A to Z, digits 0 to 9, hyphens and underscores only, so no spaces, dots, slashes, accented letters or emoji
• Not one of the reserved words, in any letter case: health, api, docs, robots.txt, favicon.ico, sitemap.xml and _next
• Not already taken by anyone on SendURL

The last rule is the one people run into. Slugs are shared across all of SendURL, not per account, because every link lives on the same snu.to domain. If someone already has snu.to/sale, you'll see "That slug is already taken — try another." Adding a word usually solves it: summer-sale-2026 or acme-sale.

Slugs are case-sensitive: snu.to/Launch and snu.to/launch are two different links, and could belong to two different people. Sticking to lowercase avoids confusion when someone types your link from a poster.

Slugs can't be changed

Once a link is created, its slug is fixed, in the console and the API alike. That's what makes a short link safe to print: the QR code and every copy of the link point at the slug. What you can change through the API is where the slug leads; see Change where a short link points.

If you need a different slug, create a new link with it, and disable the old one or let it expire.

Choosing a good custom slug

• Make it easy to say. If you'll read it out on a podcast or a stage, snu.to/ep42-notes beats snu.to/aZ3k9Q.
• Use hyphens between words. spring-menu is easier to read than springmenu.
• Avoid look-alike characters in print, such as a lowercase l next to the digit 1, or a capital O next to zero.
• Put the placement in the slug when you share the same page in several places, such as menu-window and menu-table, so each placement gets its own click count.
• Keep it short. Every character is one more someone may have to type.

For naming patterns that work across a whole campaign, see how to name short links.

How to create a link with a custom slug

1. 1.
   Sign in to the console and choose Create link.
2. 2.
   Paste the Destination URL.
3. 3.
   Under Short link slug, choose Custom and type your slug. The preview under the form shows the finished link.
4. 4.
   Choose Create short link. If the slug is taken, pick another and try again.

With the API, send slug in the body of POST /links:

curl -X POST https://api.sendurl.to/api/v1/links \
  -H "Authorization: Bearer $SENDURL_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"destinationUrl": "https://example.com/spring", "slug": "spring-menu"}'

A taken slug is 409 slug_taken, and one that breaks the rules is 400 validation_error. Every rule is listed under Create a link in the API reference.