Audio Reverser performs audio reverser as a focused single-page utility. Reverse any audio file so it plays backwards. Useful for sound design, hidden message hunting, generating tail-in transition effects, and creative audio manipulation. Files are processed entirely in your browser with FFmpeg WebAssembly. Defaults are tuned for the common case so the first run is one click, with every option that matters exposed for the moments you need to fine-tune the result.
Reach for Audio Reverser when you need a predictable result on a single file. The page works on the first visit, the controls are visible without a menu, and the output is delivered the moment the engine finishes.
The execution path is auditable from the page itself: open developer tools, switch to the Network tab, run a job. The requests you see are static-asset GETs for the engine and the page resources. The actual work is JavaScript code running against the bytes already in your tab's memory.
Audio Reverser is implemented on top of standard browser APIs. The accepted input formats are MP3, WAV, M4A, AAC, OGG, Opus, FLAC, AIFF, and WMA, decoded in the browser, processed, and re-encoded into the output format. Files up to 200 MB are well within the comfort zone of any modern browser.
The 200 MB ceiling on input size is the only fixed limit. Output files are produced in standard formats that every common viewer recognises, and the tool runs the same way regardless of how many times you have used it during the session.
Anyone who works with audio editing and conversion on a casual basis — students preparing oral submissions, voice-over artists exporting takes, streamers cleaning microphone tracks — finds Audio Reverser a quick way to get the result. The page loads in under a second, the controls are visible from a single screen, and the result downloads or copies in one click.
Audio Reverser returns the result as `{name}-edited.{ext}`. If you are running multiple jobs, the output names will not collide as long as the input names differ. You can re-run with different settings as many times as you like; each run produces a fresh file with no caching trickery in between.
As a workflow component, Audio Reverser is the part you reach for when a single, well-defined audio editing and conversion step needs to happen. It performs that step and returns a standard file you can carry into the next part of your pipeline.
The transformation in Audio Reverser is deterministic — the same input plus the same options produces the same result every run. That predictability matters when the result has to match an upstream specification or be reproducible later.
Some background on the design choices behind Audio Reverser: every option you see on the page is there because a real workflow needs it, and every option that is not shown has been deliberately omitted to keep the common case fast. The bias is toward minimal-but-complete.
If you also use a command-line tool for audio reverser, Audio Reverser is a convenient alternative for the times you are on a different machine or helping someone who is not comfortable in a terminal. The output is a standard file in the format documented above.
If you want to get the most out of Audio Reverser, three small habits help. Drag-and-drop is faster than the file picker once you get used to it. The keyboard shortcut for downloading the result is whatever your browser uses for "save link as," because the result is a normal download. And if you are working on a sensitive file, processing in an Incognito or Private window is a good extra layer — it leaves no trace in browser history when the tab closes.
If Audio Reverser appears to hang, the engine is almost certainly still working — large inputs simply take longer to process inside a browser than they would on a server with multi-core scheduling. For inputs near the 200 MB cap, give it up to a minute on a typical laptop before assuming something is stuck.
Audio Reverser is one of many single-purpose tools in the catalog. Each is built around the same single-page model. Use this one, close the tab, and come back the next time you need the same job done. None of the tools require prior knowledge of the others — each page is self-contained.
FFmpeg WebAssembly loads in your browser and applies the `areverse` filter, which reads the entire audio buffer into memory and writes it out backwards (last sample first). The output is then re-encoded to your chosen format. The result is mathematically perfect — sample-for-sample reversed audio.
Our brains process sound forward in time — onsets (like piano hits) followed by decays. Reversing turns every onset into a fade-in and every decay into a sharp ending, which is unnatural. Cymbals become "swooshes," reverb tails become pre-delays, and speech becomes pure gibberish. Sound designers love this for transitions and tension.
Almost no change. Reversed audio has the same duration, same sample count, same dynamic range — just a different temporal arrangement. The encoded file size will be within a few percent of the original, slightly different because compression algorithms react differently to different waveforms.
Not directly with this tool, but you can: (1) trim the section you want with Audio Trimmer, (2) reverse it here, (3) merge it back with Audio Merger or Audio Crossfade. This three-step workflow gives you reversed-section effects in any audio file.
Up to 200MB. Reversing requires holding the entire decoded audio in memory because the last sample comes first. For very large files (long lossless WAVs), the operation may take a while but it should still complete on any modern laptop.
You can choose MP3, WAV, OGG, M4A, AAC, FLAC, or Opus. WAV preserves the reversed audio losslessly. MP3 and AAC re-compress it (with a small quality loss as with any lossy encode). For chained editing, WAV is best.
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.
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.
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.
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.
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.
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.
Audio Reverser is free to use. The processing runs in your browser, which keeps the per-user cost low enough that the tool can be offered openly. The download is the same file the engine produced — you can use it for as many runs as you need.
Your file is processed inside your browser by standard browser APIs. The engine reads the file's bytes from your tab's memory, computes the result, and writes the result back into the tab. You can confirm what the page does by opening developer tools and watching the Network tab during a run — the requests you see are for the tool's static assets only.
Once the page is loaded, Audio Reverser 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.
Audio Reverser processes one input at a time by design — it keeps memory usage predictable on lower-end devices and makes results easier to verify. To handle a folder, run the tool once per file; the page stays loaded between runs and remembers your last-used settings, so the second run is essentially instant.
Favtoo keeps no copy of your file because Favtoo never receives your file. Audio Reverser 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.
Audio Reverser is a static page running an open-source engine in your browser, so a typical corporate firewall does not get in the way as long as it allows JavaScript to load from Favtoo. For teams that need to host it themselves on an internal network, the underlying engine (standard browser APIs) is open-source and can be packaged into a private build with the same behaviour. Reach out via the Contact page if that is something you are exploring.
Audio Reverser is a browser-only tool by design and does not expose a hosted API. The reason is the same as the privacy story: there is no Favtoo backend doing the work, so there is no service to call. If you need to script the same transformation, the underlying engine (standard browser APIs) is open-source and can be used directly from your own code.
Audio Recorder
Record from your microphone directly in the browser. Pick quality (high, medium, low), toggle echo cancellation, noise suppression and auto-gain, then save to WebM/Opus or M4A/AAC. Audio is captured locally — nothing is uploaded.
Text to Speech
Type or paste text, pick a system voice, and listen instantly. Adjust speaking rate (0.5×–2×), pitch, and volume in real time. Uses your browser's built-in Web Speech API — no cloud TTS, no API keys, no costs.
Tone Generator
Generate a pure tone at any frequency from 20 Hz to 20 kHz. Pick a sine, square, triangle, or sawtooth waveform, choose duration, amplitude, and mono/stereo. Exports a 16-bit PCM WAV file at 44.1 kHz with built-in click-preventing fades.
Silence Generator
Generate a perfectly silent WAV file of any length from 1 second up to 1 hour. Pick mono or stereo, get a 16-bit PCM WAV at 44.1 kHz. Useful as padding between clips, intro silence, leader audio for video timing, or test material.
White Noise Generator
Generate white, pink, or brown noise as a 16-bit PCM WAV file. Pick noise type, duration up to 1 hour, amplitude, and mono/stereo. Useful for sleep, focus, masking distractions, audio testing, and as a backing layer for ambient music.
Metronome
A precise browser-based metronome powered by the Web Audio API. Set BPM from 30 to 300, choose a time signature, accent the first beat, and use tap-tempo to sync. Click timing is sample-accurate using lookahead scheduling — much steadier than typical JavaScript setInterval beats.
Audio Trimmer
Trim any audio file to a precise start and end time. Outputs a lossless stream-copy by default (no quality loss, very fast) or re-encodes to MP3, WAV, OGG, or M4A. Files are processed entirely in your browser with FFmpeg WebAssembly.
Audio Splitter
Split a long audio file into N equal-length parts and download them as a ZIP. Each part is named sequentially. Great for chapterizing audiobooks, podcasts, or long DJ mixes. Runs entirely in your browser with FFmpeg WebAssembly.