Podcast episode file checker

Will the apps take this file as it is?

Drop in the file that goes in your feed. Its format, bitrate, sample rate, channels, length and tags are checked against what Apple Podcasts and Spotify publish for episode files, each with a link to the page it comes from. Then the audio is decoded to check whether a stereo file is really dual mono or has a silent channel. It all runs in your browser. Nothing is uploaded.

Drop the episode file you’re about to publish

MP3, M4A, AAC or WAV. The headers are read in a second or two; then the audio is decoded to check what’s in its channels, which takes longer for a long episode. Nothing is uploaded.

What the platforms publish

Apple Podcasts accepts MP3 or AAC in a feed, and recommends AAC in an MP4 container (.m4a). Its recommended bitrates depend on channels and sample rate: 64–128 kb/s for mono and 128–256 kb/s for stereo at 44.1 or 48 kHz, lower at 22.05 or 24 kHz.

Spotify, for shows hosted elsewhere, supports MP3 at 96 to 320 kb/s, up to 12 hours. Shows hosted on Spotify for Creators can upload MP3, M4A or WAV, mono or stereo, with no size limit, and Spotify asks that MP3 tags and embedded artwork be kept small.

Neither says anything about CBR or VBR, or publishes a file-size limit. Amazon Music and YouTube publish no episode-file requirements at all.

Uploading to a host

Most hosts re-encode what you upload, so a WAV is fine to upload even though it can’t go in a feed as it is. Buzzsprout, for one, encodes to 96 kb/s mono MP3 unless your file already is one. This tool judges the file listeners download; if your host re-encodes, check the file it publishes.