Webhook.site - Instantly generate a free, unique URL and email address to test, inspect, and automate (with a visual workflow editor and scripts) incoming HTTP requests and emails.
Free Texture Packer - Free Texture Packer is an open source tool that allows you to pack multiple images into one atlas for you games or sites.
Hookdeck - Hookdeck makes it simple to build and deploy reliable, testable, and debuggable applications that rely on webhooks.
Sprite Sheet Packer - Sprite Sheet Packer is online that you can easily use to pack sprite sheets, including data formats for CSS, LESS, and Phaser.
Svix - The enterprise ready webhooks service, open-source and in the cloud.
Sprite Monkey - Small and fast but still full-featured sprite sheet editor.