HTML Email Preview
Preview responsive HTML email code safely in a sandbox.
PreviewDeveloper Tools
Compare text and background colors to see the contrast ratio and WCAG compliance.
The code, structured data, expression, token, or sample value requested by the interface.
Choose only the settings that apply to the result you need; leave optional controls unchanged when you are unsure.
Start the task and wait for the interface to return its result or a clear setup message.
Test the result in a non-production environment. Never paste passwords, private keys, live access tokens or confidential production data.
Preview responsive HTML email code safely in a sandbox.
PreviewFormat and indent SQL queries for easier reading.
FormatConvert CSV rows into formatted JSON objects.
ConvertConvert an array of JSON objects into CSV.
ConvertCheck a public page with the W3C-compatible Nu validation service.
Validate HTMLThe code, structured data, expression, token, or sample value requested by the interface. Start with a representative input and use only the options needed for your intended result.
A transformed, generated, or diagnostic result for the submitted technical input. Treat the output as a current diagnostic snapshot rather than a permanent guarantee.
Test the result in a non-production environment. Never paste passwords, private keys, live access tokens or confidential production data.
Processing stays in the browser where the individual feature supports it. Live public checks use a protected, rate-limited site endpoint; avoid unnecessary sensitive data.
The page can be used without creating a visitor account. Your browser or device may limit unusually large files or demanding media jobs.
This Color Contrast Checker page is organised around the task described in the tool interface. Check WCAG contrast ratio between two colors. The result changes when the source data or selected options change, so it is easy to run a second comparison.
The code, structured data, expression, token, or sample value requested by the interface.
A transformed, generated, or diagnostic result for the submitted technical input.
For a typical workflow, use it to inspect a small representative sample before applying the same change in a production workflow. Start with a representative input, inspect the first result, then adjust one setting at a time if you need a different outcome.
Processing stays in the browser where the individual feature supports it. Live public checks use a protected, rate-limited site endpoint; avoid unnecessary sensitive data.