Gelato.io vs Postman vs Slate

Compact layout;HTTP requests with file upload support;Formatted API responses for JSON and XML;Image previews;Request history;Basic Auth, OAuth 1.0, OAuth 2.0, and other common auth helpers;Autocomplete for URL and header values;Key/value editors for adding parameters or header values. Works for URL parameters too.;Use environment variables to easily shift between settings. Great for testing production, staging or local setups.;Keyboard shortcuts to maximize your productivity;Automatically generated web documentation;Mock servers hosted on Postman’s cloud;API monitoring run from Postman cloud

Import from Swagger or API Blueprint; Sync with Github; Guide editor with live preview; Automatic API Explorer; Customise look-and-feel to match your company's brand;Custom domains (developer.yoursite.com); Developer registration;Doc Search

Clean, intuitive design — with Slate, the description of your API is on the left side of your documentation, and all the code examples are on the right side. Inspired by Stripe's and Paypal's API docs. Slate is responsive, so it looks great on tablets, phones, and even print.;Everything on a single page — gone are the days where your users had to search through a million pages to find what they wanted. Slate puts the entire documentation on a single page. We haven't sacrificed linkability, though. As you scroll, your browser's hash will update to the nearest header, so linking to a particular point in the documentation is still natural and easy.;Slate is just Markdown — when you write docs with Slate, you're just writing Markdown, which makes it simple to edit and understand. Everything is written in Markdown — even the code samples are just Markdown code blocks!;Write code samples in multiple languages — if your API has bindings in multiple programming languages, you easily put in tabs to switch between them. In your document, you'll distinguish different languages by specifying the language name at the top of each code block, just like with Github Flavored Markdown!;Out-of-the-box syntax highlighting for almost 60 languages, no configuration required.;Automatic, smoothly scrolling table of contents on the far left of the page. As you scroll, it displays your current position in the document. It's fast, too. We're using Slate at TripIt to build documentation for our new API, where our table of contents has over 180 entries. We've made sure that the performance remains excellent, even for larger documents.;Let your users update your documentation for you — by default, your Slate-generated documentation is hosted in a public Github repository. Not only does this mean you get free hosting for your docs with Github Pages, but it also makes it's simple for other developers to make pull requests to your docs if they find typos or other problems. Of course, if you don't want to, you're welcome to not use Github and host your docs elsewhere!