Windows · Android
Music playback and sound-correction software for Windows and Android. Everything applied between source and output is written on screen — and when nothing should be applied, nothing is.
v0.10.8 · 2026-10-19 · Windows 10/11 ·
all releases
Android app on Google Play · v0.5.5 · Android 8.0+
System-wide headphone correction Starts from a measurement
DSD64 – DSD1024 upsampling Filters are synthesised
Bit-perfect exclusive output Shows what is leaving now
Network playback and PC remote Never through a relay
Either one stands on its own. Use both and they do more together.
Keep your apps — the same correction covers everything your PC plays, with DSD upsampling and bit-perfect output on top.
The music on your device, sent to a USB DAC untouched. Complete on its own, and a remote when a PC is around.
From the files on your phone to the PC and network players in your home — one app, one place.
Play a track in Apple Music or YouTube Music and tap [CastFi sound] on Home: that app’s sound gets your headphone correction and effects on its way to the USB DAC or the phone. The screen is never recorded (Android 10+).
No silent full-device scan. CastFi indexes only the folders you pick, organised by album, artist, track and folder — so recordings such as call logs never enter your library.
Connect a USB DAC and DSD files travel untouched, while PCM keeps its original format. The screen always shows exactly what is leaving the phone.
Correction matched to the headphones you actually own, plus bass, clarity and width effects and crossfeed. Turn it on — no numbers required.
The phone becomes the PC’s remote — transport, volume, search, playlists and sound settings. Browse the PC’s library on the phone and stream the originals, let the PC take over DSD conversion the phone can’t keep up with, and pair once to listen away from home.
Send a track to a network player in your home, or play the library stored on your NAS. Pick a folder in OneDrive to play and keep its music on the phone too. Nothing is relayed through an outside server.
Install CastFi on any device running Android 8.0 or newer. No account, no sign-in.
Point CastFi at the folders that hold your music. It reads only those, and you can add or remove them at any time.
Earphones or an external DAC — CastFi picks the right path for whatever is attached, and finds your PC if it is running.
You can see what the source is, what is being applied, and what is going out. Turn the correction off and nothing at all is touched.
The Android app is a complete player on its own. PC features are added when a PC is around — nothing is locked away when it is not.
Run CastFi for Windows and your phone becomes the remote. The two connect directly on your home network — your music never passes through an outside server.
CastFi never uploads your music files, and it never asks you to create an account. Anonymous usage statistics and crash reports can be switched off in settings at any time.
Files and the index live on the device only. Playback, correction and library work all happen locally.
The Android app asks for no name, email or phone number. Install it and start listening.
Statistics and crash reporting have separate switches, and the policy spells out exactly what is sent.
No. The phone alone plays your local library with headphone correction and USB DAC output. PC features are an optional extra when CastFi for Windows is on the same Wi-Fi.
Put the phone and the PC on the same Wi-Fi, open the CastFi window on the PC, then pick the PC from the device icon at the top right of CastFi on the phone. If the 6-digit confirmation code on the PC matches the phone, click Allow on the PC. If the PC does not appear in the list, see the fixes on the support page.
DACs that follow USB Audio Class 2.0. Whether a given DAC accepts DSD untouched varies by model — once connected, the app shows what that DAC can actually take. Your Android device needs to support OTG.
Android requires notification access before an app can show and control what another music app is playing. CastFi works fine without it — its own playback and the rest of the app are unaffected — and notification content is never stored or transmitted.
No. Files and the library index stay on the device. Exchanges with a PC, NAS or network player happen directly on your home network, never through a relay. If you connect cloud storage (OneDrive), songs come straight from Microsoft to the phone, and CastFi only reads the files in your cloud.
Both the PC and Android apps support 12 languages (Korean, English, Japanese, German, French, Spanish, Portuguese, Traditional and Simplified Chinese, Italian, Indonesian and Vietnamese), switchable in the app's settings.
Get the Android app on Google Play, and the Windows app right here.
