- https://codepen.io - Try html, css and javascript snippets
- http://beeceptor.com - Useful for testing APIs endpoints that are not available
- https://mailtrap.io - Fake smtp testing server. Dummy smtp email testing
- https://localhost.run/ - Expose local servers to the internet
- https://apiary.io - Platform for API Design, Development & Documentation
- https://www.draw.io - Online diagram software for making charts and diagrams
- http://console.re - Remote JavaScript Development Console
- https://pipedream.com - Enables lambda functions like request bin
- https://www.elastic.co/solutions/apm - Open Source Application Performance Monitoring
- https://www.datadoghq.com - Modern monitoring & analytics
- https://mixpanel.com - Product and User Analytics for Mobile, Web, and Beyond
- https://zeit.co/ - Cloud platform for static sites and Serverless Functions
- https://www.backblaze.com/ - Cloud Storage with a free tier and a API Similar to S3
- https://cloudinary.com - Cloud service that offers a solution to image management pipeline
- https://heroku.com - Cloud Application Platform
- https://dot.tk - Free Domains
- https://letsencrypt.org - Free SSL Certificates
- https://upstash.com - Redis (free tier)
- https://www.mongodb.com/cloud/atlas/register - Mongo (free tier)