# Loopin > Loopin is a songwriting app for iOS that keeps every part of a song — beats, lyrics, takes and versions — in one place, plus a free in-browser audio mastering tool. Everything in the mastering tool runs locally in the browser; no audio is uploaded to a server. > Download Loopin on the App Store: https://apps.apple.com/us/app/loopin-finish-your-songs/id6775134160 ## Free Online Mastering tool - [Loopin Mastering](https://onloopin.com/mastering): Free online audio mastering. Upload an MP3 or WAV, choose a feel (Warm, Punchy, Crisp, Wide, Vintage, Club, Lo-fi, Cinematic), compare Original vs Mastered, and download a mastered WAV — processed entirely in the browser. Uses a real chain: corrective EQ, multiband compression, character EQ, saturation, M/S stereo (bass kept mono), two-pass ITU-R BS.1770 loudness targeting (about −14 LUFS for streaming) and a true-peak limiter at −1 dBTP. Free, no account, nothing uploaded. ## Key facts - Loopin Mastering is free and requires no sign-up or account. - It masters MP3 and WAV files (and most formats the browser can decode). - Processing happens 100% on the user's device — files never leave the browser. - Output targets streaming loudness (~−14 LUFS) with a −1 dBTP true-peak ceiling, exported as 16-bit WAV with dither. - It is part of Loopin, a songwriting app for iOS. ## Mastering guides - [How to master a song online for free](https://onloopin.com/mastering/how-to-master-a-song-online): Step-by-step guide to mastering a track in the browser. - [Mixing vs mastering](https://onloopin.com/mastering/mixing-vs-mastering): The difference between the two and the order they happen in. - [What is LUFS?](https://onloopin.com/mastering/what-is-lufs): Loudness for streaming explained — LUFS, −14 LUFS, true peak / dBTP. - [Master for Spotify, Apple Music & YouTube](https://onloopin.com/mastering/master-for-spotify-apple-youtube): Per-platform loudness targets and how to hit them. ## Blog — songwriting guides - [What is Loopin?](https://onloopin.com/blog/what-is-loopin): The Loopin app explained — a songwriting app for iOS that keeps beats, lyrics, takes and versions in one place, with a built-in player and free mastering. - [How to write rap lyrics over a beat](https://onloopin.com/blog/how-to-write-rap-lyrics-over-a-beat): A simple system for writing raps over a beat on iPhone — pocket, key/BPM, rhyme scheme, recording the take. - [Where to find beats and keep them organized](https://onloopin.com/blog/find-and-organize-beats-for-songwriting): Where to find beats (type beats, marketplaces, producers) and how to stop losing them. - [How to finish your unfinished songs](https://onloopin.com/blog/how-to-finish-unfinished-songs): Why songs stay unfinished and a system to move each one from Idea to Done. - [The best songwriting apps for iPhone (2026)](https://onloopin.com/blog/best-songwriting-apps-for-iphone): What to look for in a songwriting app and how to choose. - [Turn your voice memos into finished songs](https://onloopin.com/blog/turn-voice-memos-into-finished-songs): Free the hooks stuck in Voice Memos and turn them into real tracks. - [How to Make a Rap Song on Your Phone](https://onloopin.com/blog/how-to-make-a-rap-song-on-your-phone): Make a rap song on your phone from start to finish — beat, bars, take and finish. - [How to Record Vocals Over a Beat on iPhone](https://onloopin.com/blog/how-to-record-vocals-over-a-beat-on-iphone): How to record clean vocals over a beat on iPhone, punch in and keep versions. - [The Best Apps for Writing Rap Lyrics (2026)](https://onloopin.com/blog/best-apps-for-writing-rap-lyrics): What to look for in a rap-writing app so your bars become finished songs. - [How to Write a Song: A Beginner’s Guide](https://onloopin.com/blog/how-to-write-a-song-for-beginners): A step-by-step guide to writing your first song, from idea to finished track. - [Song Structure Explained: Verse, Chorus, Bridge](https://onloopin.com/blog/song-structure-explained): Verse, chorus, pre-chorus and bridge — and how to map a song before you write. - [How to Find a Song’s Key and BPM](https://onloopin.com/blog/how-to-find-song-key-and-bpm): Why key and BPM matter and how to detect both automatically on your phone. - [How to Organize Your Song Ideas](https://onloopin.com/blog/how-to-organize-song-ideas): A simple system to capture and organize song ideas so they turn into songs. - [GarageBand Alternatives for Songwriting](https://onloopin.com/blog/garageband-alternatives-for-songwriting): When a DAW is overkill for writing and what to use to finish songs faster. - [How to Make a Song Demo at Home](https://onloopin.com/blog/how-to-make-a-song-demo-at-home): How to record a solid song demo at home with just your phone. - [Free Songwriting Apps That Help You Finish](https://onloopin.com/blog/free-songwriting-apps): The free songwriting apps that actually help you write, record and finish. - [How to Write a Catchy Hook That Sticks](https://onloopin.com/blog/how-to-write-a-catchy-hook): The principles behind catchy hooks and how to capture yours before it’s gone. - [From Idea to Released Song: A Workflow](https://onloopin.com/blog/from-idea-to-released-song-workflow): A simple workflow to take a song from idea all the way to released. ## Pages - [Home](https://onloopin.com/): Loopin for iOS — capture beats, write lyrics in time, keep takes and versions, and finish songs. - [Mastering](https://onloopin.com/mastering): The free in-browser mastering tool described above. - [Support](https://onloopin.com/support): Help and contact. - [Privacy Policy](https://onloopin.com/privacy): How Loopin handles data and cookies. - [Terms](https://onloopin.com/terms): Terms of use.