Being one of the most popular classic wave editing apps for iOS, Hokusai is the best choice for sound designers, musicians, podcasters, journalists, educators and hobbyists since 2011.

The audio editor has very simple, uncluttered UI to allow users focus on their tracks. Behind the simple interface however you can find lots of useful tools and capabilities, such as fade in/out, normalise volume levels, reverse time, and basic synthesis. With this powerful audio/music editor on iPhone, you can record tracks, import tracks from Music library, import audio/music from iPhone or a cloud service, trim, cut, copy, paste, delete tracks or your selection, edit multiple tracks side-by-side, mix them together, export to Wave or MPEG 4 (AAC) format, transfer to your computer via a cable, or cloud service, send to another app on your iOS device, upload to various cloud services.

Multi-track audio editor
Edit many tracks side-by-side, mix them together, export to Wave or MP4 format
Editing and more
Trim, full cut, copy, paste, delete, various filters and effects.
Free audio editor
Comes free with a set of useful tools such as fade in/out, normalise volume levels, reverse time, etc. Free to download and use with basic features and optionally upgrade to full version for more advanced tools and features.
User friendly
Streamlined to give you a clean, clear view, pinch & swipe gestures to zoom right in and fiddle with fine detail, etc.
Free or Paid?
Hokusai comes free with a set of useful tools such as fade in/out, normalise volume levels, reverse time, and basic synthesis. If you need more power, you can upgrade from inside the app to add new tools and effects, including: Per-track volume/mute/panning, selecting across multiple tracks at once, presets and favorites, grain synthesis, noise gating, time-stretching, pitch-bending, echo, reverb, modulation (AM & FM), resonance, distortion, grunge, vocal leveling, monster voice, high/low/band-pass/notch-cut filter and more — many of which can be previewed live.
Download
Get this app from Apple App Store below.
Updated Aug 2022: this article was originally published in May 2017 and has since been updated. in this update, the old screenshot was replaced by the new one captured from Hokusai Audio Editor V2.5.6 on iPhone.