cryptotools provides a browser-based way to find MD5 and SHA1 hashes, do URL encoding and decoding, Base64 encoding and decoding, and a few other useful things. It is written in Ruby, using Sinatra for the web front-end.
Many years ago, I started using a PHP-based tool called Cryptomak to do simple things like MD5 and SHA1 hashing for password comparisons. I gradually started to add my own features, until the PHP code became large and difficult to maintain.
Having gotten interested in Ruby recently, I decided to try to re-implement it in Ruby, and needing a simple web front-end, I chose Sinatra.
Try it on Heroku.
Install dependencies with:
bundle install --path vendor/bundle
Start it directly with:
bundle exec ./cryptotools.rb
Then, browse to http://localhost:4567
You can also start it via Rack:
bundle exec rackup config.ru
Then, browse to http://localhost:9292