Audio Frequency Analyzer
Identify the dominant frequencies in any audio file and map them to musical notes (A4 = 440 Hz). Useful for transcription, tuning instruments, finding the key of a song, and identifying noise sources.
About Audio Frequency Analyzer
Identify the dominant frequencies in any audio file and map them to musical notes (A4 = 440 Hz). Useful for transcription, tuning instruments, finding the key of a song, and identifying noise sources.
All analysis happens entirely inside your browser using the Web Audio API. Your audio file never leaves your device — there is no upload, no account, no tracking. Closing the tab fully erases the file from memory.
Browser-based audio analysis trades a little speed for total privacy. Server tools can crunch big lossless files faster on dedicated CPUs, but they require uploading your file. Here, decoding and analysis run on the same hardware you're holding.
Related tools
About Audio Frequency Analyzer
Audio Frequency Analyzer runs the audio editing and conversion job locally inside your browser. Identify the dominant frequencies in any audio file and map them to musical notes (A4 = 440 Hz). Useful for transcription, tuning instruments, finding the key of a song, and identifying noise sources. The work happens on your machine, the result is generated on your machine, and the page exposes the controls you need to drive it without burying them in menus.
The processing pipeline is straightforward: your input is parsed by standard browser APIs, transformed according to the options you select, and serialised back into a downloadable result. Accepted input formats are MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA. The 200 MB per-file ceiling matches what a typical browser tab can handle without paging to disk.
Audio Frequency Analyzer is shaped for the gap between "I'll do it by hand" and "I'll script it." When the job is small enough that automating it would take longer than doing it, but annoying enough to want a focused tool — that is the situation this page is built for.
The browser sandbox isolates the page's JavaScript from the rest of the system, the same way it isolates every other tab you have open. Audio Frequency Analyzer works inside that sandbox: it reads the file you give it, processes it with standard browser APIs, and writes the result back. Nothing leaves the page's memory unless you choose to download or copy it.
On limits: 200 MB per file is the ceiling. Output formats and quality settings are listed in the controls panel above, and they apply to every run.
Audio Frequency Analyzer sits in a small group of related tools. Useful neighbours include Audio Spectrum Analyzer, Audio Pitch Changer, Audio Equalizer, and Audio BPM Detector. They are designed to compose: the output of one is a sensible input to the next, so a multi-step task is usually a sequence of single-click operations.
Audio Frequency Analyzer sees the most use from musicians sharing demos and language learners reviewing speech, but the design is intentionally generic enough that you do not need a specialist background to get a good result. The defaults aim at the most common case so a first-time user can get the right output without changing any settings.
Once the engine finishes, `{name}-edited.{ext}` is offered as an immediate download. There is no preview gate, no email-wall, and no "register to download" intermediary — the file is yours the moment it is ready.
Audio Frequency Analyzer is built around steady iteration on a small set of options rather than feature creep. Every additional setting attracts a slightly different audience, but a long settings panel makes the common case slower for everyone. The current controls reflect what users of the tool actually use.
From a product perspective, Audio Frequency Analyzer is one of the simplest possible expressions of "do one thing well." The catalog contains dozens of related tools that each handle a slightly different audio editing and conversion task, and every one is a separate page rather than a tab inside a larger app. That separation keeps each tool fast to load and easy to bookmark.
A few practical tips that experienced users of Audio Frequency Analyzer pick up over time. First, keep your default browser updated — the engine relies on standard web APIs and newer browser versions are noticeably faster than ones from a few years ago. Second, close other heavy tabs before processing a large input; the engine shares CPU and memory with whatever else is open. Third, if you re-run the same kind of job often, your last-used settings are remembered for the rest of the tab session, so subsequent runs are essentially one click.
Audio Frequency Analyzer is built around the moment of need: a focused page you open when you have a specific task, complete the task, and close. The catalog contains many adjacent tools so the same model serves the surrounding parts of a typical audio editing and conversion workflow.
Common gotchas worth flagging: Audio Frequency Analyzer only accepts MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA, so if your file is in another format you will need to convert it first. The 200 MB ceiling is per-file, not per-session; you can run as many separate jobs as you like, but a single oversized input will be rejected on load.
That is essentially everything Audio Frequency Analyzer does and how it does it. Open the tool above, drop in your input, and the work happens in the page. If you find yourself reaching for it often, bookmark the page — it loads quickly on subsequent visits, and your most-recent settings are remembered for the rest of the session.
How it works
- 1Open Audio Frequency Analyzer in your browser. The page loads quickly and the tool is ready to use the moment it becomes interactive.
- 2Drop a MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA file onto the upload area, or click to pick one from your device.
- 3Adjust the options to match what you need. Sensible defaults cover the most common case, so you can usually skip this step.
- 4Hit the run button. standard browser APIs does the work in your browser tab.
- 5Download the result as `{name}-edited.{ext}`. The file is generated in your browser and saved through your normal download flow.
- 6Run additional jobs as needed. The same controls and defaults apply on every run.
Common use cases
- Convert a voice memo into a format your editor can open using Audio Frequency Analyzer.
- Extract the audio from a video so it can be edited separately.
- Stitch several voice notes into a single playable file.
- Compress a music demo small enough to share over messaging.
- Boost a quiet interview recording to a normal listening level.
- Convert a band's rough mix into a format mastering software accepts.
- Trim the cough out of the first ten seconds of a podcast take.
- Record a quick test tone to verify a microphone setup.
- Re-encode a lossless track into a portable format for the gym.
- Split a long mixtape into individual track files.
FAQ
How does it work?
The audio is decoded to PCM, then analyzed with an FFT to extract frequencies present and their relative energy. Dominant frequencies are mapped to musical notes using equal temperament (A4 = 440 Hz, semitone = 12√2 frequency ratio). The result lists the most prominent pitches in the audio.
What can I learn from this?
The musical key of a song (the most common note tells you the tonic). Tuning of an instrument (a note that should be A4 = 440 Hz showing 442 Hz means it's slightly sharp). Noise source identification (a peak at exactly 60 Hz means AC mains hum). Vocal range analysis (highest and lowest notes).
How accurate are the note mappings?
Within a few cents (1 semitone = 100 cents). For pure tones the accuracy is excellent. For complex audio (chords, multiple instruments, distorted sounds), the result is the strongest single peak. To analyze chords properly you'd need a more sophisticated polyphonic analyzer.
How is this different from "Audio Spectrum Analyzer"?
Spectrum Analyzer shows the entire frequency profile as a chart (great for diagnostics). This Frequency Analyzer focuses on identifying specific peak frequencies and mapping them to musical notes (great for tuning and pitch identification).
Will it find the key of a song?
Approximately. The most common dominant note is usually the key center, but this is a heuristic. Modal music, modulating songs, and atonal music can confuse the analysis. For accurate key detection, dedicated tools like Mixed in Key are more reliable.
How big a file can I analyze?
Up to 200MB. Most analysis happens on a sample of the audio rather than the whole file, so even long files complete in a few seconds.
Why is in-browser audio processing slower than online tools?
Server-side tools use multi-threaded native FFmpeg running on dedicated CPUs with fast disks and parallel pipelines. Our engine is FFmpeg compiled to WebAssembly, which runs single-threaded inside your browser tab and has no access to native hardware acceleration. That makes browser-based jobs typically 3–8× slower than a server. The trade-off is total privacy: your audio file is never uploaded, never logged, and never stored — closing the tab erases everything from memory immediately. For most clips up to a few minutes the wait is small, and for sensitive recordings (voice memos, drafts, confidential meetings) the privacy gain is well worth it.
Is my audio uploaded?
No. Everything runs entirely inside your browser tab using FFmpeg compiled to WebAssembly. The file is read into local memory only, processed in the same tab, and the result is offered as a direct download. Nothing is transmitted to any server, no account is required, no analytics are tied to your file, and closing the tab discards every byte from memory.
How big a file can I process?
The file picker accepts audio inputs up to about 1 GB, which is well above what mainstream "free tier" online converters allow. The real ceiling is your device — everything runs inside your browser tab, which shares memory with the rest of the page. Most podcasts, songs, and voice memos sit comfortably under that limit even on a phone. If a very large lossless WAV or FLAC ever fails, trim it first or transcode to MP3 / Opus to bring the size down before re-running the tool.
Which audio formats are supported?
MP3, WAV, OGG (Vorbis and Opus), FLAC, M4A (AAC), AAC, Opus, AIFF, and WMA all decode reliably via FFmpeg WASM. Output formats depend on the specific tool — most editing tools default to MP3 (universal) or WAV (lossless) but expose a format picker so you can pick the one that fits your downstream player or DAW.
Which browsers are supported?
Recent Chrome, Edge, Firefox, Safari, and other Chromium-based browsers all work. The tool relies on WebAssembly and SharedArrayBuffer, which require the page to be served over HTTPS with the right cross-origin headers — this site is configured correctly by default. On phones the same code runs but is slower than on a desktop because mobile CPUs are weaker.
Is there a watermark, sign-up wall, or usage cap?
No. The tool is completely free, requires no account, attaches no watermark, applies no usage caps, and shows no popup ads on your output. Because the work happens on your own device, there is no per-user quota for us to enforce — your hardware and browser memory are the only limits. The download is the file you would get from running FFmpeg locally, nothing more, nothing less.
Do I need a specific browser to use Audio Frequency Analyzer?
Audio Frequency Analyzer works in any modern browser released in the last few years — Chrome, Edge, Firefox, Safari, Brave, Arc and the major Chromium derivatives are all supported. The underlying engine relies on widely-supported web APIs, so there is nothing exotic to install. If you are on a very old browser version and the tool fails to load, updating to the latest release of your preferred browser is the only fix needed.
Will Audio Frequency Analyzer keep working in a year?
Audio Frequency Analyzer is updated whenever the underlying engine releases an improvement or a bug fix. Because the tool is delivered as a static page, every visit fetches the latest version automatically — there is no "version" to manage on your end. If a particular release ever changes default behaviour, the change is documented on Favtoo's changelog so you can confirm what shifted.
Are jobs run with Audio Frequency Analyzer stored anywhere?
Favtoo keeps no copy of your file because Favtoo never receives your file. Audio Frequency Analyzer runs entirely in your browser, the input is held only in your tab's memory, and closing the tab discards it. There is no opt-in cloud history, no "recent jobs" panel synced to an account, and no server-side retention to configure — the architecture simply has nowhere for your file to be stored.
Does Audio Frequency Analyzer work with screen readers?
Audio Frequency Analyzer uses native HTML controls wherever possible, which means keyboard navigation, focus rings, and screen-reader labels work the way the platform expects. The drop zone accepts files via the keyboard-accessible file picker as well as drag-and-drop, and result downloads use standard browser download flows. If you spot an accessibility gap, Favtoo treats it as a bug worth fixing.
Will Audio Frequency Analyzer keep working if my Wi-Fi drops mid-task?
Once the page is loaded, Audio Frequency Analyzer can complete jobs without an active internet connection — the engine is bundled with the page, so there is no per-job network call. The initial page load does require a connection (to fetch the static assets), but after that you can disconnect entirely and the tool will still work. This is a side-effect of the local-first architecture, not a deliberate "offline mode" feature.
Why did Audio Frequency Analyzer reject my input?
Failures usually fall into one of three buckets: the input is in an unsupported format, the input is over the size cap, or the input is structurally malformed (a truncated download, a partial export, or a stream the engine does not recognise). The first two are easy to confirm — check that your file is one of MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA and that it is below 200 MB. For the third, opening the file in its native viewer first is the fastest way to confirm the source is intact.
Is Audio Frequency Analyzer lossless?
Audio Frequency Analyzer is built to preserve quality wherever the underlying audio format allows it. Operations that are mathematically lossless (e.g. structural transformations, lossless re-encoding) round-trip with no perceptible change. Operations that involve a lossy codec inevitably introduce small artefacts at the byte level, but the defaults aim at the sweet spot where output looks or sounds the same to a normal viewer or listener while still being meaningfully smaller or faster than the input.