Content Security Policy headers are one of those things every web team knows they should have but often skips — the syntax is verbose, the directives are easy to misconfigure, and a wrong policy breaks the app silently in production. Writing a small generator in Go removes the human error and makes CSP a first-class part of your build.
Why CSP matters and where it fails
CSP is an HTTP response header that tells the browser which resources — scripts, styles, images, fonts — are allowed to load and from where. A well-crafted policy defeats cross-site scripting (XSS) attacks even when an attacker has already injected content into your HTML, because the browser simply refuses to execute disallowed scripts.
The problem is maintenance. Teams start with a permissive policy (default-src 'self'), then add exceptions for every CDN and vendor widget until the header looks like an allow-list for the entire internet. At that point the policy is longer than it is useful.
Building a generator means you describe intent — "scripts from our CDN only, no inline styles, report violations to this endpoint" — and get a validated, reproducible header string every time.
