Security

CSP Nonce Generator

Generate a random Content Security Policy nonce value for inline script or style allowlisting.

Last reviewed: April 30, 2026Free toolMethodology

CSP Nonce Generator

These fields start with sample inputs. Keep them or replace them, then run the tool to show a fresh result.

Number fields accept plain values and common formatted input such as 250000, 250,000, or 1,234.56.

Result

Calculating the sample result.

Why it matters

Nonce-based CSP setups need fresh, high-entropy values, and teams often want to test nonce handling quickly during implementation work.

When to use

  • Testing CSP integrations
  • Generating example nonces for docs or local demos
  • Understanding what a nonce value should look like

Inputs & Outputs

Inputs

  • Byte length controls how much randomness is generated before Base64 rendering.

Outputs

  • Nonce value shows the generated Base64 token.
  • CSP snippet preview shows how the nonce would appear inside a header fragment.

Nonce generation method

The tool generates secure random bytes with Web Crypto and Base64-encodes them into a nonce suitable for CSP header use.

CSP nonces should be fresh, unpredictable, and generated per response

Worked example

1

CSP rollout test

An engineer wants a 16-byte nonce to test a CSP header locally.

Inputs

  • Byte length: 16

Steps

  • Generate secure random bytes
  • Base64-encode the result
  • Render a sample CSP fragment

Result

  • The output can be used to test nonce-aware markup and headers.

Edge cases & caveats

  • Nonce reuse weakens the protection offered by nonce-based CSP.
  • This tool is useful for demos and debugging, but production apps should generate a fresh nonce per response automatically.

Frequently Asked Questions

Can I reuse the same nonce everywhere?

No. A nonce should be generated freshly for each response that uses a nonce-based policy.

Why does a CSP nonce look like Base64?

Because nonces are typically random bytes rendered into a compact text format that is easy to place in headers and markup.

Keep going

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