FID / INP Checker
Measure Interaction to Next Paint (INP) and First Input Delay (FID) in your browser using PerformanceObserver. Check PageSpeed Insights scores and get tips to improve interaction responsiveness.
Live Browser Measurement
Click "Start Measuring", then interact with this page (click buttons, type in inputs) to record real INP and FID values.
PageSpeed Insights Score Input
Enter scores from PageSpeed Insights to get a rating instantly.
FID (deprecated) measured only the first interaction. INP measures the worst interaction latency throughout the entire page lifetime and is now a Core Web Vital as of March 2024.
Tips to Improve Interaction Responsiveness
Break up JavaScript tasks longer than 50ms using setTimeout, requestIdleCallback, or scheduler.yield() to allow the browser to respond to user inputs.
Avoid heavy computation in click/keydown handlers. Move expensive work off the main thread to Web Workers when possible.
Large DOM trees increase style recalculation and layout time. Aim for fewer than 1,500 DOM nodes for optimal performance.
Use code splitting and lazy loading to reduce the amount of JS that must be parsed and executed during page load.
Reading layout properties (offsetHeight, scrollTop) after writing to the DOM causes layout thrashing. Batch reads and writes separately.
CSS animations that use transform and opacity can run on the compositor thread and bypass the main thread entirely.
Frequently Asked Questions
What is INP?
INP (Interaction to Next Paint) measures the latency of all interactions on a page throughout its lifetime. It replaced FID as a Core Web Vital in March 2024. Good INP is under 200ms.
What is FID?
FID (First Input Delay) measured only the delay from the first user interaction. It was deprecated in March 2024 and replaced by INP which measures all interactions.
How do I improve INP?
Break up long JavaScript tasks, minimize DOM size, reduce third-party script impact, avoid forced synchronous layouts, and use CSS transitions instead of JS animations.
Is the FID / INP Checker free to use?
Yes, the FID / INP Checker is 100% free with no registration, no hidden fees, and no usage limits. All processing happens locally in your browser, ensuring complete privacy.
Is my data safe with this tool?
Absolutely. The FID / INP Checker processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.
Does the FID / INP Checker work on mobile devices?
Yes, the FID / INP Checker is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.
Do I need to create an account to use this tool?
No account or registration is needed. Simply open the FID / INP Checker in your browser and start using it immediately. There are no sign-up walls or usage restrictions.
Does this tool follow Google's latest guidelines?
Yes, the FID / INP Checker is built following current Google Search guidelines and best practices. We regularly update the tool to reflect changes in search engine requirements.
Which browsers are supported?
The FID / INP Checker works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.
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About FID / INP Checker
FID / INP Checker is a free, browser-based tool in our SEO Tools collection. Everything runs locally on your device — no uploads, no sign-up, and your data stays private.