Supported formats
What AudioTools can open and save, what each format is good for, and where browsers differ.
| Format | Type | Typical bitrate | Best for | Open | Export | Limits |
|---|---|---|---|---|---|---|
| MP3.mp3 | Lossy | 128 to 320 kbps; 192 kbps is a common balance | music libraries, podcasts and sharing when you cannot know what the listener uses | Everywhere | Everywhere, using a bundled encoder (no browser encodes MP3 natively) | Each re-encode loses a little more detail, and there is no true gapless support without extra tags. |
| WAV.wav .wave | Uncompressed | 1,411 kbps at CD quality (44.1 kHz, 16-bit, stereo); higher at 24-bit or 96 kHz | editing, mastering, sampling and handing audio between programs without quality loss | Everywhere | Everywhere (8, 16, 24 and 32-bit integer or 32-bit float) | Large files: about 10 MB per minute at CD quality. The classic format stops at 4 GB, which RF64 extends. |
| M4A.m4a .mp4 .m4r | Lossy | 96 to 256 kbps; 128 to 192 kbps is typical | iPhone and Apple Music libraries, ringtones (.m4r), and better quality than MP3 at the same size | Everywhere (Apple Lossless inside M4A uses a bundled fallback decoder) | AAC where the browser can encode it, otherwise a bundled AAC encoder | The same file can hold lossless Apple Lossless (ALAC), so the extension alone does not tell you whether it is lossy. |
| AAC.aac | Lossy | 96 to 256 kbps; 128 to 192 kbps is typical | streaming-style files and hardware that expects a plain AAC stream | Everywhere | AAC where the browser can encode it, otherwise a bundled AAC encoder | A bare ADTS stream has no real tag container, so title, artist and cover art are usually missing. |
| FLAC.flac | Lossless | about 500 to 1,000 kbps, roughly 50 to 60 percent of the WAV size | archiving a CD collection and keeping masters at about half the size of WAV | Everywhere | Everywhere, using a bundled encoder | Still several times larger than MP3 or AAC, and not every car stereo or older player supports it. |
| OGG.ogg .oga | Lossy | 64 to 500 kbps; quality 5 is about 160 kbps | games, open-source projects and royalty-free distribution | Everywhere | Everywhere (a bundled encoder is used where the browser has none) | Less hardware support than MP3 or AAC, and largely superseded by Opus for new work. |
| Opus.opus .ogg | Lossy | 6 to 510 kbps; 64 to 128 kbps is transparent for most music | voice notes, podcasts, streaming and small files with high quality at low bitrates | Everywhere | Everywhere (browser encoder when present, otherwise a bundled one) | Not accepted by many older car stereos, portable players and some editing software. |
| WebM.webm .weba | Lossy | depends on the codec inside; Opus at 64 to 128 kbps is typical | recordings made in the browser and audio taken from web video | Everywhere | Where the browser can encode Opus or Vorbis | Poor support in desktop audio players and editors, and on older Apple software. |
| AIFF.aiff .aif .aifc | Uncompressed | 1,411 kbps at CD quality, the same as WAV | Mac-centred production and handing files to studios that ask for AIFF | Everywhere (read by built-in code, not the browser) | Everywhere | Same size as WAV, stops at 4 GB, and has weaker tag support than most formats. |
| AMR.amr .3gp | Lossy | 4.75 to 12.2 kbps for AMR-NB (8 kHz mono); up to 23.85 kbps for AMR-WB | speech on very small files, and reading old phone recordings | Everywhere (bundled decoder) | Everywhere (bundled encoder, narrowband speech only) | Designed for speech only: music sounds thin and narrow. Narrowband AMR is 8 kHz mono. |
| WMA.wma | Lossy | 48 to 192 kbps; 128 kbps is typical | opening an old music collection; not recommended for new files | Everywhere (bundled decoder) | Everywhere (bundled encoder, WMA version 2) | Some old files are DRM-protected and cannot be opened by any tool. Tag and software support has faded. |
| MP4.mp4 .m4v | Container | audio track usually 96 to 256 kbps AAC | phone videos, downloads and web video | Everywhere (the audio track is read, the video is ignored) | Not applicable (audio only) | Some files carry audio codecs (such as AC-3) that a browser cannot decode directly. |
| MOV.mov .qt | Container | AAC audio is usually 128 to 256 kbps; PCM audio is uncompressed | iPhone and Mac video, and professional video exchange | Everywhere (the audio track is read, the video is ignored) | Not applicable (audio only) | Rarely used outside the Apple ecosystem, and ProRes files are very large. |
| MKV.mkv .mka | Container | depends on the audio codec inside | multiple audio tracks, subtitles and chapters in one file | Everywhere (the first audio track is read when the codec is supported) | Not applicable (audio only) | Audio codecs such as DTS or TrueHD may not be decodable in a browser. |
Opening and saving: how it works
Opening a file uses the decoders built into your browser first, because they are fast. When a browser cannot decode a format (WMA, AMR, Apple Lossless, AIFF and a few others, or any format on a browser without WebCodecs), AudioTools loads its own decoder from this site, only when needed.
Saving works the same way. Browsers rarely encode MP3 or FLAC, so those encoders are bundled and loaded when you first save in that format. AAC and Opus use the browser's encoder where there is one.
Which formats you can save depends on your browser. This page describes the general picture; each tool checks, live, what your browser can do before you start, and it tells you plainly if a format is not possible instead of failing at the end. A video's audio track is read when its codec can be decoded, which covers most files but not every DTS or Dolby track.
Browser support
| Browser | Built-in audio codecs | What it means here |
|---|---|---|
| Chrome and Edge (desktop), Chrome on Android | Decode and encode | AAC encoding depends on the operating system and is not available in desktop Linux builds; MP3 and FLAC encoders are bundled. |
| Firefox (desktop, version 130 and later) | Decode; encode Opus and PCM | No built-in AAC encoder, so AAC output uses a bundled encoder. Decoding relies on the system codecs. |
| Firefox on Android | No WebCodecs | All decoding and encoding use bundled WebAssembly codecs. Everything works, but conversions are slower and use more memory. |
| Safari 26 and later (macOS, iOS, iPadOS) and every browser on iOS | Decode; encode Opus and AAC | iOS browsers use the Safari engine, so they behave the same. Memory limits on phones are tighter than on computers. |
| Safari before version 26 | Partial | Missing codecs fall back to bundled decoders and encoders, with the same trade-off as Firefox on Android. |
Based on published browser documentation and usage data. Behaviour can differ between devices and operating system versions.