Serverless URL shortener using Firebase RTDB:

A lightweight URL shortener API built with Wrangler and Firebase Realtime Database.

This project is intended for personal use and small-scale deployments, and runs with minimal resource usage.

Deploy your own instance using the button below:

🚀 Key features:

• Rate limiting: daily request quotas and burst traffic protection (anti-spam).

• No duplicates: prevents storing identical URLs, saving database space.

• No sign-up: no account creation, credit card, or personal data required.

• GDPR compliant: built with privacy in mind.

• Highly configurable: customize behavior to your needs.

• Firebase backend: stores URL mappings in Firebase Realtime Database.

• Minimal REST API: fast, efficient, and lightweight.

• Serverless: runs on Cloudflare Workers free plan with strict resource limits.

🌐 API access:

Endpoint	Rate limit	Maintainer	Privacy
https://nsh.nde-code.workers.dev/	1 req/IP/sec, 10 new links/IP/day	Me	privacy.md

CORS is enabled only for the URL-posting endpoint, for clear security reasons.

Check the status page if you experience latency or other issues while using my public online instance.

Notes:

• Feel free to use my public instance, but be aware of the limits.

• Keep an eye on the repository to catch any changes to these limits.

• The Firebase RTDB database is located in Belgium on my public instance, so users from distant countries may experience some latency.

• I've enabled Smart Placement routing for a better experience.

📚 Available endpoints:

In this section, I've used https://your-worker.org.workers.dev/ in the cURL command examples. If you've deployed your own instance of the project, replace it with your instance's domain. Otherwise, use my free public instance at https://nsh.nde-code.workers.dev/, as explained above.

1. [POST]/post-url - Create short URL:

Create a short URL from a long URL. Saves to database and applies rate limiting.

Request body:

Field	Type	Description
long_url	string	Required. Original URL to shorten (must be valid)

Note: request fails if JSON contains unexpected fields or URL exceeds max length.

Response codes:

Code	Description
201	URL successfully shortened and saved
200	URL already shortened previously (returns existing short link)
400	Invalid body, missing long_url, unexpected field, or invalid URL
409	Hash collision (different URL, same hash)
429	Rate limit exceeded (time-based or daily write limit)
500	Server error (config, environment, or generation failure)
503	KV quota exceeded or database read failure
507	Firebase entry limit reached

Example request:

curl -X POST "https://your-worker.org.workers.dev/post-url" \
-H "Content-Type: application/json" \
-d '{"long_url": "https://nde-code.github.io/"}'

Example response:

{
"success": "https://your-worker.org.workers.dev/url/11i7yev0000000"
}

2. [GET]/url/:code - Redirect to original URL:

Redirect to the original long URL using the short code.

Path parameters:

Parameter	Type	Description
code	string	Required. Unique short ID

Response codes:

Code	Description
301	Permanent redirect (verified link)
302	Temporary redirect (unverified link)
400	No valid ID in path
404	Link not found in database
500	Server error
503	Request timeout or storage connection failure

Example request:

curl -i "https://your-worker.org.workers.dev/url/11i7yev0000000"

3. [GET]/urls - List all URLs:

Retrieve a paginated list of shortened links.

Security: requires valid admin key (see authentication).

Query parameters:

Parameter	Type	Description
count	number	Number of links to retrieve (default: config value, max: restricted)
cursor	string	Last item key from previous page (use next_cursor from response)

Response codes:

Code	Description
200	Successfully returned URLs
400	Invalid count or cursor parameter
401	Invalid or missing API key
429	Rate limit exceeded
500	Server error
503	Database retrieval failure

Example request:

curl "https://your-worker.org.workers.dev/urls?count=2" \
-H "x-api-key: YOUR_ADMIN_KEY"

Example response:

{
"urls": {
"11i7yev0000000": {
"long_url": "https://nde-code.github.io/",
"post_date": "2024-05-12T10:00:00.000Z",
"is_verified": true
},
"vgsyqs00000000": {
"long_url": "https://www.google.com/",
"post_date": "2024-05-12T11:30:00.000Z",
"is_verified": false
}
},
"next_cursor": "vgsyqs00000000",
"has_more": true
}

4. [PATCH]/verify/:code - Verify URL:

Mark a shortened URL as verified.

Security: requires valid admin key (see authentication).

Path parameters:

Parameter	Type	Description
code	string	Required. Unique short ID

Response codes:

Code	Description
200	Link verified successfully (or already verified)
400	No valid ID in path
401	Invalid or missing admin key
404	Link not found
429	Rate limit exceeded
500	Server error
503	Database update failure

Example request:

curl -X PATCH "https://your-worker.org.workers.dev/verify/11i7yev0000000" \
-H "x-api-key: YOUR_ADMIN_KEY"

5. [DELETE]/delete/:code - Delete URL:

Remove a shortened URL and decrement the counter.

Security: requires valid admin key (see authentication).

Path parameters:

Parameter	Type	Description
code	string	Required. Unique short ID

Response codes:

Code	Description
200	Link deleted successfully
400	No valid ID in path
401	Invalid or missing admin key
404	Link not found
429	Rate limit exceeded
500	Server error
503	Database deletion failure

Example request:

curl -X DELETE "https://your-worker.org.workers.dev/delete/11i7yev0000000" \
-H "x-api-key: YOUR_ADMIN_KEY"

6. [PATCH]/sync-counter - Resynchronize counter:

Recalculate and sync the metadata counter to match actual URLs in Firebase. Useful for fixing race conditions or desynchronization.

Security: requires valid admin or monitoring key (see authentication).

Note: the admin key can be used to manually resynchronize the counter when needed. The monitoring key is also accepted, allowing the endpoint to be called automatically by external monitoring tools (as with /health) or scheduled services.

Response codes:

Code	Description
200	Counter resynced successfully (returns new count)
401	Invalid or missing admin key
429	Rate limit exceeded
500	Server error
503	Database communication failure

Example request:

curl -X PATCH "https://your-worker.org.workers.dev/sync-counter" \
-H "x-api-key: YOUR_ADMIN_KEY"

Example response:

{
"success": "Counter synchronized successfully.",
"new_count": 42
}

7. [GET]/health - Service health check:

Check service health: configuration, database connectivity, counter integrity, capacity, and KV storage.

Security: requires valid monitoring key (see authentication).

Response codes:

Code	Description
200	All systems operational
206	Degraded but operational (one or more non-critical issues)
503	Service unavailable (critical failure)

Example request:

curl -X GET "https://your-worker.org.workers.dev/health" \
-H "x-api-key: YOUR_MONITORING_KEY"

Example response (Healthy):

{
"status": "healthy",
"timestamp": "2026-04-26T20:17:27.121Z",
"checks": {
"config_valid": true,
"firebase_reachable": true,
"counter_accessible": true,
"kv_store_available": true
},
"message": "All systems operational."
}

🔐 Authentication:

Protected endpoints require either header format:

• Authorization: Bearer <MONITORING_or_ADMIN_KEY>
• x-api-key: <MONITORING_or_ADMIN_KEY>

Note: trying to access the administration endpoints on my public instance is completely forbidden.

🖥️ Developer documentation:

For setup, configuration, and deployment using Wrangler CLI, see the developer guide.

⚖️ License:

This project is licensed under the Apache License v2.0.

🎯 Author:

Created and maintained by Nde-Code.

Don't hesitate to open an issue or a pull request if you have any questions or would like to contribute.