BSK File

What are BSK files and how to open them

Are you having problems opening a BSK file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BSK files.

What is a BSK file?

A .BSK file is a Bespoke Synth Savestate file.

Bespoke Synth Savestate files store the full state of a session in Bespoke Synth, a modular audio and music creation tool for Mac, Windows, and Linux. These files capture the current arrangement of modules (oscillators, sequencers, mixers, etc.), all control settings, routing and patch cables, UI layout (positions, zoom, scroll), audio settings (sample rate, buffer size, input/output devices), tempo, transport status, tuning, user preferences, and recorded loops, so that the session can be closed and restored exactly as it was.

They are written by Bespoke Synth when the user chooses Save State (via Ctrl-S or the Save State button), and read back by Bespoke Synth via Load State (Ctrl-L or Load State button). Users typically use them to save ongoing creative work, reload saved states later, or share state files as "source" files for their patches and compositions. Bespoke's documentation refers to these files as the source format for patches and sessions.

Savestate files are plain text (JSON-formatted), human-readable, and contain named fields corresponding to modules, control values, preferences, layout, and audio/Routing settings. Field names visible in the files include MODULES, TEMPO, RECORD_BUFFER_LENGTH_MINUTES, AUDIO_OUTPUT_DEVICE, UI_SCALE, SAMPLERATE, TRANSPORT, ENABLED, LAYOUT (with subfields like WIDTH, HEIGHT, POSITION_X / Y), TUNING, etc.

As a technical identifier, savestate files begin with a byte signature starting at a fixed offset where ASCII characters show "modules" following a JSON-style structure (e.g. containing "modules" : [ ) and include strings like "SET TEMPOCONTROLSEPARATOR", "RECORD_BUFFER_LENGTH_MINUTES", "AUDIO_INPUT_DEVICE", "UI_SCALE", etc.

How to open BSK files

Important: Different programs may use files with the BSK file extension for different purposes, so unless you are sure which format your BSK file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single BSK opener which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of BSK files. Remember, different programs may use BSK files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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