Free · No account · No file uploads
Audio and subtitle tools that run on your device
Check a recording, fix its channel layout or prepare captions without sending the file to a server. Choose the problem you need to solve below.
Check recordings before editing
LUFS meter
Measure integrated loudness, sample peaks and estimated true peak without uploading your recording.
Open free tool →Audio channel inspector
Find silent channels, uneven levels and stereo phase cancellation before editing or transcribing.
Open free tool →WAV file diagnostic
Check RIFF headers, audio format chunks and declared file lengths. Read-only, with no upload.
Open free tool →Microphone test
Check your input before recording.
Open free tool →Fix channels and sample rates
Stereo to mono converter
Mix channels or keep only the left or right channel. Preview and download a mono WAV.
Open free tool →Split stereo into mono files
Download each channel separately as a mono WAV. Useful for interviews recorded on separate tracks.
Open free tool →Audio sample-rate converter
Resample audio to 8, 16, 22.05, 24, 44.1 or 48 kHz and download a PCM WAV.
Open free tool →Validate and convert subtitles
Subtitle validator
Check SRT and WebVTT syntax, invalid times, overlaps, empty cues and reading speed.
Open free tool →SRT to WebVTT converter
Convert SRT subtitles to WebVTT, with timing checks before download.
Open free tool →WebVTT to SRT converter
Convert WebVTT captions to SRT for video editors and subtitle uploads.
Open free tool →What stays local, and what does not?
These ten tools process audio or caption text in your browser. They do not call a speech provider or require a SoundHalo subscription. Microphone testing asks for microphone access only when you start a test.
Audio decoding depends on your browser and device memory. Try a short recording first, keep the original file and check exported audio in your destination editor. The LUFS meter is a diagnostic tool, not certified broadcast compliance equipment. Subtitle checks do not certify accessibility or compare captions against speech.
Privacy-respecting page and categorical tool-use analytics may be sent to PostHog, unless you opt out through DNT or GPC. Your recording, filename and caption text are not included. Read the privacy policy.
Need a transcript from speech?
Transcription and noise cleanup are separate cloud tools with uploads and processing limits. Compare all audio tools or read our recording guides.