# Convert Audio to MP3, WAV, or Opus > Audio Converter is a browser-based tool that converts audio files between MP3, WAV, Opus, M4A, FLAC, OGG, and AAC without uploading anything. It decodes audio in-browser via the Web Audio API and re-encodes locally using a built-in MP3 encoder or your browser's WebCodecs encoder for Opus. Drop one file or a whole batch and download the results as a ZIP. Your recordings never leave your device. Live tool: https://lofttools.com/tools/audio-video-tools/audio-converter Category: Audio and Video ## What it does - Input formats — MP3, WAV, M4A, FLAC, OGG, Opus, AAC, WebM audio - Output formats — MP3 (lamejs, 96–320 kbps), WAV (16-bit lossless PCM), Opus (Ogg container via WebCodecs) - Tunable bitrate for MP3 and Opus (96 / 128 / 192 / 256 / 320 kbps) - Batch mode — convert multiple files at once, download as ZIP - Opus-to-MP3 conversion for WhatsApp voice notes that ChatGPT/email clients reject - 100% browser-based — Web Audio API decode + local encode, no upload - Up to 100 MB per file ## How it works 1. **Drop your audio file** — Drag and drop one or more audio files (MP3, WAV, M4A, FLAC, OGG, Opus, AAC) onto the upload area, or click to browse. 2. **Choose output format** — Pick MP3, WAV, or Opus. For MP3 and Opus, select a bitrate (96–320 kbps; default 192). 3. **Convert** — Click Convert — encoding runs locally in your browser. 4. **Download** — Single files download directly. Batch conversions are packaged as a ZIP. ## FAQ ### Which audio formats can I convert from and to? Input formats: MP3, WAV, M4A/MP4 audio, FLAC, OGG, Opus, AAC, and WebM audio. Output formats: MP3 (lossy, tunable bitrate), WAV (lossless 16-bit PCM), and Opus (lossy, Ogg container). Any supported input can be converted to any of the three outputs. ### Is WAV output lossless? Yes. WAV output is 16-bit PCM — a lossless encoding of the decoded audio. MP3 and Opus are lossy; they discard some audio data to achieve smaller file sizes. ### Does any audio upload to a server? No. Everything runs in your browser. The Web Audio API decodes the file locally, and the encoder (lamejs for MP3, WebCodecs for Opus) runs in the same tab. No audio data leaves your device at any point. ### Why does my browser refuse to convert to Opus? Opus encoding requires WebCodecs, which is supported in Chrome 94+ and Edge 94+ but not in Safari or Firefox as of 2026. If conversion to Opus fails, switch to MP3 or WAV — both work in all modern browsers. ### Can I convert WhatsApp voice notes? Yes. WhatsApp exports voice recordings as .opus files. This tool converts them to MP3 locally, which is accepted by ChatGPT, email clients, and most audio apps. No upload required. ## Tips - **Opus files from WhatsApp** — WhatsApp voice messages export as .opus — a format most apps and AI chat tools refuse. Drop the file, pick MP3, and get a universally accepted version in seconds. - **Use WAV when editing in a DAW** — WAV output is lossless 16-bit PCM — ideal for importing into Audacity, GarageBand, or any DAW that will re-export later. Converting to MP3 twice causes double-lossy artifacts; go WAV instead. - **Batch convert a whole folder** — Select all files at once to convert them in one pass. Results come as a single ZIP. Handy for migrating a podcast archive or a music library to a new format. ## Privacy — what we do not do This tool runs entirely in the browser via WebAssembly. Your file never reaches a Loft Tools server. Specifically: - **No upload.** The file bytes load into the browser tab's memory and process on your own CPU. Open DevTools → Network and observe zero outbound requests carrying file data while Convert Audio to MP3, WAV, or Opus runs. - **No AI training on your file.** Loft does not train models. We could not train on a file we cannot see. - **No content scanning.** No virus, copyright, or content-moderation pass against your file. The bytes are not accessible to us. - **No server-side log of file contents, filenames, or EXIF metadata.** Cloudflare edge captures URL and truncated IP for abuse defense (standard CDN behaviour). Cloudflare Web Analytics records anonymous page hits, no cookies, no PII. Nothing about your file content reaches any log. - **No retention.** Close the tab and the file leaves browser memory. No backups exist on our side because no copy ever existed on our side. - **No account.** No email, no signup, no auth, no telemetry tied to you. - **Offline-capable after first visit** (PWA). Once you've loaded a tool, it caches; later sessions work without internet. For high-sensitivity files, run the tool once online to warm the cache, then disconnect before processing. Compare with upload-based services: each transmits your file to a processing server. Even over HTTPS, each has logs, retention windows, and subpoena exposure. Loft has none of these because the server architecture does not include your file. ## More - All tools: https://lofttools.com/tools - Category: https://lofttools.com/tools/audio-video-tools - LLM index: https://lofttools.com/llms.txt