See a "pretty" version of your API. Goggles installs a little tiny Sinatra app on a URL prefix and serves any JSON responses that come back as a prettyprinted HTML page. There are browser add-ons that do a great job with this sort of thing, but I wanted something I could live-link from API docs....

Rack middleware for logging request data to Honeycomb.

Add rel=preload headers to Rack applications

Ignores X-Forwarded-Host header to prevent malicious redirects

Rack middleware for in-app purchase receipt verification and product listing.

Rack middleware to decode JWT and append it to the rack environment

Rack Middleware for JSON APIs accessed cross-domain from legacy browsers Firefox version 4 does not support response headers for cross-domain requests. This middleware intercepts all requests and if the X-WRAP-RESPONSE is set, the response will be wrappped in JSON like {header: ..., body: ...}

LESS CSS preprocessing for Rack apps.

Uses the mail library for sending exceptions

A Rack middleware to publish directries containing media files as podcast

Would be useful to enable OpenID authorisation with your Ruby/Rails-based blog, personal website or whatever.

Middleware that communicates impending shutdown to a load balancer via NACKing (negative acking) health checks. Provided you have at least two load-balanced instances, this allows you to shut down or restart an instance without dropping any requests. Your app needs to inform the middleware when...

Automatically generate webservice endpoints for Newsstand

Transparently secure your rack application with google. For test rigs etc.

Rack::NonCache is a rack middleware that disables HTTP browser caching.

A simple CMS system built on top of sinatra for lighweight but feature rich sites

Automatically generate REST APIs for Passbook registration.

Parse post data by MessagePack

Rack::ProcessName is rack middleware to set the ruby process name to whatever request is currently being processed.

Provides a profiler page of the ruby execution which has infomation of gc and object allocation.