Accept Language Header Builder
Generate Accept-Language header values with q weights for locale testing.
What the Accept Language Header does
Generate Accept-Language header values with q weights for locale testing. A localization test can send en-US first, then en, then es with lower weights Adjust the controls and the preview updates immediately, so you can dial in exactly what you want and copy the result straight into your project — no build step and no account.
One thing to keep in mind: Headers only express preference; the server decides the final locale.
Private and in your browser
Everything runs locally in your browser. Your input is never uploaded, so the tool stays fast and works offline, and the copy and download buttons always use the current result shown in the output panel.
Frequently Asked Questions
What does the Accept Language Header do?
Generate Accept-Language header values with q weights for locale testing. A localization test can send en-US first, then en, then es with lower weights.
What should I keep in mind?
Headers only express preference; the server decides the final locale
Does it upload my input?
No. The Accept Language Header runs entirely in your browser — your input is never uploaded, and it keeps working offline once the page has loaded.
Practical utilities for front-end design and implementation work.