CSP Header Generator — Content Security Policy Builder
Build Content Security Policy headers with an easy form for each directive, with both HTTP header and meta tag output.
How it works
- 1Configure your options above
- 2Click "Generate CSP Header" — processing happens in your browser
- 3Copy or download the result
What to do next
About CSP Header Generator
CSP Header Generator is a developer tool that runs in your browser. Build Content Security Policy headers with an easy form for each directive, with both HTTP header and meta tag output. The page you are reading is the same workspace you will use to do the work: pick a file or paste your input, choose the options that matter to you, and the tool produces the result on your device.
Under the hood, CSP Header Generator uses standard browser APIs to do the actual work. Input runs through the same engine, with a per-file ceiling of 0 MB so memory usage stays predictable on lower-end laptops and tablets. The engine ships as part of the page bundle, so once the page is loaded the tool keeps working even if your network connection drops.
CSP Header Generator is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
CSP Header Generator is structured so the question "where is my file processed?" has a single answer: in your browser tab. The engine, the controls, and the result panel are all on one page. Navigating away or closing the tab clears the page's memory the way it does for every other tab.
The only practical limit is the 0 MB per-file ceiling, which keeps the tool responsive across a wide range of devices. Run the tool ten times in a row, run it ten thousand times — it behaves the same way and produces the same quality of result.
For multi-step jobs, CSP Header Generator sits next to CORS Header Generator, JWT Encoder (HS256), and TOTP Validator. None of them depend on each other — you can use CSP Header Generator on its own — but together they cover the common variations of the task this page exists to handle.
Common audiences for CSP Header Generator include engineers debugging API payloads and data analysts wrangling JSON, but plenty of people land on the page through a one-off search and never come back — that is also fine. The tool is built to be useful even when you only ever need it once.
When the job finishes, CSP Header Generator hands you the result as a sensibly named file. Filenames are derived from your input where possible, so a quick batch of jobs leaves you with a tidy folder rather than a pile of generic "output (3)" files. Nothing is auto-saved on Favtoo's side because nothing was ever sent there.
CSP Header Generator keeps the control set focused. Every option on the page is there because a real workflow needs it, and the defaults aim at the most common case so a first-time user can get the right output without changing any settings.
CSP Header Generator is structured around the idea that a useful tool should be its own page. Open the page, do the work, close the tab — the page is the entire product. There is no onboarding flow because there is nothing to onboard into.
Tips from users who reach for CSP Header Generator regularly: process one input first to confirm the settings produce what you expect before committing to a batch; treat the page as the working surface and avoid leaving large jobs running in a backgrounded tab where the browser may throttle JavaScript; and if a particular file fails, check whether the source is intact by opening it in its native viewer — most "tool errors" are actually input errors.
CSP Header Generator runs as a regular web page, so there is no install step or permission grant before the first run. The page can be audited by viewing the source or by watching the developer-tools Network tab while a job runs.
For most failure modes, refreshing the page and re-running the job is enough — the engine has no persistent state to corrupt. If the same input fails twice in a row, the input itself is most likely the problem (a truncated file, an unexpected variant of the format, or a stream the engine does not recognise).
That is the whole tool. Use CSP Header Generator for as long as it stays useful to you, and if it does, the catalog has many more tools built the same way. Each applies the same single-purpose discipline, so the way you used this page transfers to the next one you try.
How it works
- 1Land on the CSP Header Generator page. The tool is ready to use the moment the page renders.
- 2Add your developer input by dropping it onto the page or browsing for it.
- 3Adjust the options to match what you need. Sensible defaults cover the most common case, so you can usually skip this step.
- 4Hit the run button. standard browser APIs does the work in your browser tab.
- 5Download the result. The file is generated in your browser and saved through your normal download flow.
- 6Re-run with different settings as often as you want. Each run produces a fresh output and the original file on disk is never modified.
Common use cases
- Generate boilerplate from a single specification line using CSP Header Generator.
- Inspect a regex against a test string before committing it.
- Pretty-print a minified blob during incident triage.
- Hash a string for a quick reproducibility check.
- Validate a config blob before pushing to staging.
- Decode a token to confirm its claims during a debugging session.
- Convert between data formats while wiring up an integration.
- Compare two API responses to spot a regression.
FAQ
What is a Content Security Policy?
CSP is an HTTP header that helps prevent XSS, clickjacking, and other code injection attacks by specifying which content sources browsers should trust.
Which directives should I set?
At minimum, set default-src. Then override specific directives like script-src and style-src as needed for your application.
What does 'self' mean?
The 'self' keyword allows content from the same origin (protocol + host + port) as the document.
Should I enable upgrade-insecure-requests?
Yes for HTTPS sites — it tells browsers to rewrite HTTP resource URLs to HTTPS before fetching.
Can I use this with a meta tag?
Yes — the tool outputs both the HTTP header format and an equivalent HTML meta tag.
Is this generated locally?
Yes — the CSP header is built in your browser with no server involved.
Is CSP Header Generator keyboard accessible?
CSP Header Generator uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
Why use CSP Header Generator instead of a paid online tool?
Desktop apps usually have more advanced features but require installation, maintenance and (often) a licence. Paid online tools are convenient but route your file through their servers and gate downloads behind accounts. CSP Header Generator sits in between: free, instant, and private, but intentionally narrow in scope. For one-off jobs and the common developer utility operations, it is usually the lowest-friction choice; for highly specialised work, a dedicated app is still the right answer.
Will I notice a difference in the output from CSP Header Generator?
CSP Header Generator is built to preserve quality wherever the underlying developer format allows it. Operations that are mathematically lossless (e.g. structural transformations, lossless re-encoding) round-trip with no perceptible change. Operations that involve a lossy codec inevitably introduce small artefacts at the byte level, but the defaults aim at the sweet spot where output looks or sounds the same to a normal viewer or listener while still being meaningfully smaller or faster than the input.
Why does CSP Header Generator feel slow on large inputs?
Most jobs finish in seconds. Speed scales with input size and with how many CPU cycles your browser tab has available — the engine runs in your browser, so it shares resources with whatever else you have open. For inputs near the 0 MB ceiling, expect anywhere from a few seconds to roughly a minute on a typical laptop. Closing other heavy tabs noticeably speeds things up.
Can I self-host CSP Header Generator for my team?
CSP Header Generator is a static page running an open-source engine in your browser, so a typical corporate firewall does not get in the way as long as it allows JavaScript to load from Favtoo. For teams that need to host it themselves on an internal network, the underlying engine (standard browser APIs) is open-source and can be packaged into a private build with the same behaviour. Reach out via the Contact page if that is something you are exploring.
Is CSP Header Generator really free?
CSP Header Generator is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Is there a programmatic version of CSP Header Generator?
CSP Header Generator is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.