Reference & Lookups
5 tools — all free, all browser-side.
HTTP Status Codes
Complete reference of all HTTP status codes — searchable with descriptions.
MIME Types Reference
Searchable lookup of file extensions and their MIME / content types.
Common Ports Reference
Searchable list of well-known network ports and the services that use them.
CIDR & Subnet Reference
Searchable reference of CIDR prefixes, subnet masks, host counts and private IP ranges.
HTTP Headers Reference
Searchable reference of common HTTP request and response headers and what they do.