Was asked to document some common tools that developers use to work within the API space. Not comprehensive but a start.
SOAPUI SoapUI - The Home of Functional Testing
WSDL Analyzer - https://www.wsdl-analyzer.com/
JSON Formatter https://chrome.google.com/webstore/detail/json-formatter/bcjindcccaagfpapjjmafapmmgkkhgoa?hl=en
Regex Tester: http://regexpal.com/
XPath Tester: http://www.xpathtester.com/xpath
Base 64 endcoder/decoder: https://www.base64decode.org/
SAML Encoder/decoder: http://www.ssocircle.com/en/1203/saml-request-online-decoder-encoder/
URL encoder/decoder: http://meyerweb.com/eric/tools/dencoder/
Android Asset Studio (useful for making app icons): http://romannurik.github.io/AndroidAssetStudio/index.html
JSON Lint: http://jsonlint.com/
JSON Web Tokens - jwt.io
For information specific to the CA API Management products.
http://wiki.ca.com and type api into the search box for all product based documentation.