ProToolBox

Code Snippet Tester - Pretty JSON & Sandboxed HTML Preview

Choose JSON for JSON.parse pretty-print or HTML for escaped source plus a sandboxed iframe (no scripts). Live stats, one-tap copy-no upload, no signup, no watermark.

Format JSON and preview HTML locally

Pretty JSON for APIs and logs; HTML mode shows safe source and a locked-down preview for layout checks.

1 Pick type · 2 Paste · 3 Run · 4 Copy

Snippet input

Output & preview

Try . More JSON tools: formatter · validator · HTML escape.

Runs in this tab only-no server upload, no signup, no watermark.

Paste a snippet-stats update as you type when Live is on.

What you will see: Pretty JSON or escaped HTML plus an optional iframe preview. Next: Run or Live.

Output appears here

Paste JSON or HTML or tap sample.

Next: HTML preview is not a JS playground-sandbox blocks scripts. For full fidelity use your app; for JSON use validator before production. · All tools

  • Works in your browser-runs on your device, not our servers
  • No upload required-your input stays in this tab
  • Free and instant
  • No account needed
  • Private by default-the same ProToolbox promise on every page

What this is for

Code Snippet Tester - Pretty JSON & Sandboxed HTML Preview helps you format, validate, and encode before paste: works in your browser, no account needed. JSON, YAML, Base64, URLs, escapes-check here first, then ship to PRs, Slack, or configs.

  • Re-validate after every payload edit
  • Copy from the panel-nothing leaves your device until you do
  • Local run for tokens and internal data
  • Green here, then paste into production paths

Security: Fast correctness pass only-secrets still go through your team’s review.

Why use a local snippet tester

Quickly sanity-check payloads and markup without pasting proprietary JSON into random sites. The HTML iframe stays sandboxed so scripts cannot run-ideal for static layout peeks.

How it works

  1. Pick JSON or HTML.
  2. Paste your snippet and click Run or enable Live.
  3. JSON: we JSON.parse then pretty-print. HTML: escaped source + sandboxed srcdoc.
  4. Copy output back into your editor or ticket.

FAQ

  • Why doesn’t my <script> run? The preview iframe uses sandbox="" with no allowances-by design.
  • Trailing commas in JSON? JSON.parse rejects them-match your runtime.
  • Large payloads? Turn off Live if the tab slows.

Bookmark this page for webhook payloads, CMS fragments, and quick JSON eyeballing-everything stays in your tab until you copy.

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