App URL Formatting

You might notice that your app’s URL is different from the name you chose. This is because we convert your app name into a valid URL format to comply with DNS rules and ensure it works everywhere.

The Problem

DNS has strict rules for URLs. Your creative app names might not fit these rules (and could even break the internet). Here are some examples of invalid names:

❌ "My Awesome App!"     → Invalid characters
❌ "2024-best-project"   → Can't start with number
❌ "_super_app_"         → No underscores allowed
❌ "this-is-a-really-really-really-really-really-long-app-name" → Too long

The Solution

We automatically convert your app name to a valid URL:

✅ "My Awesome App!"     → my-awesome-app
✅ "2024 Best Project"   → a2024-best-project
✅ "_super_app_"         → super-app
✅ "123-numbers"         → a123-numbers

How It Works

1. Convert to lowercase - DNS is case-insensitive
2. Remove special characters - Only letters, digits, and hyphens allowed
3. Replace spaces/underscores - Becomes hyphens
4. Remove invalid starts - Numbers/hyphens moved or removed, prepending ‘a’ if needed
5. Trim to 63 chars - DNS label limit
6. Ensure uniqueness - Add hash if needed
7. Collapse multiple hyphens - -- becomes -

DNS Rules (RFC 1035)

Every URL part must:

• Be 1-63 characters long
• Start with a letter
• Use only a-z, 0-9, and -
• Not start/end with -
• No spaces or special characters

Examples

Your App Name	Generated URL
Hello World!	hello-world.fastapicloud.dev
2024 Project	a2024-project.fastapicloud.dev
My_API_v2	my-api-v2.fastapicloud.dev
Test!!!	test.fastapicloud.dev

Why Not Restrict Input?

We want you to focus on building your app, not worrying about URL rules. You type what makes sense to you, and we handle the technical requirements. Everyone’s happy!