FastSampler — a VST3 sampler that starts in a moment

Measured, not claimed

Speed is the whole design.

FastSampler is written the way an audio engine should be: plain structs, memory taken once at the start, SIMD in every hot loop, and no framework underneath it. Two external libraries go into the build — Dear ImGui for the interface and WavPack for lossless sample storage. That is the entire dependency list, and it is why the plugin is smaller than most of the icons in a modern installer.

A real instrument, loaded

Celeste v4: 768 samples, four zone collections, 48 kHz, a 181.56 MB sample bank. Clicking Load put it on the keyboard in about two tenths of a second, and it sits in 44 MB of RAM — because every zone keeps only its preload in memory and streams the rest off the disk while it plays.

768 samples 181.56 MB bank 44 MB RAM ~0.2 s to load

The specifications panel of the plugin, listing an instrument's sample count, sample rate, bit depth, preload size and file sizes. — The browser reads an instrument's specifications before you load it.

Measured on a Windows 10 desktop with the instrument on a local drive, build 640. Load time was sampled from the click to the last change in the plugin's own RAM counter, so it is an upper bound at about 40 ms of resolution. Your machine and your disk will give you different figures.

The interface

Everything on one surface.

Four tabs, no floating windows, no wizards. The player holds sixteen instrument slots; the zone editor is where samples become an instrument; the instrument editor is the effect rack and the collections it acts on. The interface draws itself in software or on the GPU, whichever costs you less, and it scales to whatever your screen is.

The FastSampler player tab: an instrument browser on the left, sixteen instrument slots, a velocity curve, and volume and filter envelopes with draggable handles. — **Player.** Browser, slots, velocity curve, and the envelopes for the loaded instrument. The status line carries RAM, CPU and the live voice count.

The zone editor: a waveform with its envelope drawn over it, zone detail fields, and a sample map spanning the keyboard and the velocity axis. — **Zone editor.** The waveform with its envelope and loop markers, every zone parameter, and the map itself — key range across, velocity up.

The instrument editor: a list of zone collections on the left with solo, mute and disable buttons, and an effect rack on the right holding a round robin script and a sustain pedal effect. — **Instrument editor.** Zone collections down the left, their effect rack on the right, and the bus each collection goes out on.

What it does

A sampler, finished.

Not a player for somebody else's library. FastSampler takes WAV files and gives you back an instrument, in a format you own, that you can hand to anyone.

Sample mapping

Key and velocity zones, round robins, release samples. Up to 4096 zones and 128 zone collections in one instrument, 512 voices each, and sixteen instruments in a single plugin instance.

Disk streaming

Every zone holds a preload in RAM — 8192 frames by default, and yours to set — and streams the rest as it plays. Big libraries cost you disk, not memory.

An effect rack per collection

Twenty-two effect types, eight to a collection: gain, parametric EQ, filters, tuning, envelopes, time stretch, spectral morph, legato, router, sustain pedal.

Modulation you draw

Any effect parameter takes up to eight drivers. A driver is a CC, a velocity, an LFO, legato speed or note hold, put through a 128-point curve you draw by hand.

Sampled legato

Real transition samples, triggered from the played interval and its speed — with that speed available as a modulation source of its own.

Keyswitch routing

The router turns one collection into a set of rules: a condition, and the collections it hands the note to. Articulation switching without a script.

Lossless storage

Sample banks are packed with WavPack. Measured 2.45× smaller than raw PCM, and the samples that come back out are bit-for-bit the ones that went in.

Instrument authoring

Build the instrument from inside the plugin: one .fsi and one .fsb beside it. A small YAML file next to them carries your notes, your credit and your artwork.

Busses and outputs

Per-instrument busses, so microphone positions and articulations reach your mixer on their own channels instead of a single stereo pair.

The settings tab: interface scaling and size, a choice of graphics renderer, tooltips, volume metering, the disk streaming buffer size, and the zone capacity of an instrument. — **Settings.** The streaming buffer, the zone capacity an instrument reserves and the renderer are yours to set. Nothing here needs an internet connection.

How it compares

Most samplers are a delivery system.

Two of the columns below are not samplers at all: the Spitfire Audio plugin and Orchestral Tools' SINE player exist to put one publisher's catalogue on your keyboard, and they will not open a WAV of your own. Kontakt is a real sampler and a very good one — it also brings an account, an installer and a 52 GB complete install. FastSampler is the small end of that scale: turn your recordings into an instrument, and nothing else.

Drag the table sideways →

	FastSampler	Kontakt 8	Spitfire Audio plugin	SINE player
Maps your own samples	Yes	Yes, full version	No	No
Builds instruments in the plugin	Yes	Yes, full version	No	No
Account or licence manager	None	Native Access	Spitfire Audio app	Orchestral Tools account
Installation	Copy one folder	Installer + Native Access	Installer + app	Installer + app
Needs to reach the internet	Never	To install and activate	To sign in and download	To activate and download
Disk space for the player	2.8 MB	2 GB minimum, 52 GB full	Not published	Not published
Plugin formats	VST3	VST3, AU, AAX, standalone	VST3, AU, AAX	VST3, AU, AAX
Instrument format	Yours: one .fsi + one .fsb	Proprietary, .nki	Spitfire libraries only	Orchestral Tools libraries only
Scripting	No — a fixed rack and drawn curves	KSP	No	No

Kontakt figures are Native Instruments' own published system requirements (2 GB free disk space, 52 GB for a complete installation) and Native Access 2 is required to install. Spitfire Audio's libraries are downloaded and managed through the Spitfire Audio app, signed in to a Spitfire account; SINE needs an Orchestral Tools account and one trip online to activate. Checked September 2026 — vendors change these, so check for yourself before you rely on it.

And what it is not. FastSampler ships no library and no factory content — it is a tool, not a catalogue. There is no scripting language: what the rack and the curves do is what it does. It is VST3 only, so there is no AU and no AAX yet. And the current release is honestly a test build: it is used daily to build real orchestral instruments, but it has not been through anybody else's studio.

Get it

Copy one folder. That is the install.

Builds for both platforms are published from a separate public repository. Version 1.0.3, build 636.

Windows 10 / 11, 64-bit

Download the ZIP, unpack it, and put FastSampler.vst3 into your VST3 folder:

C:\Program Files\Common Files\VST3\

Latest release →

macOS 11 or later

Universal — Apple Silicon and Intel. Through Homebrew:

brew tap M5292/fastsampler
brew install --cask fastsampler

Or take the ZIP →

The plugin opens no network connections. The only address it ever touches is a link you click yourself in an instrument's notes, which it hands to your browser. Settings, logs and curve presets stay beside the plugin on Windows and in ~/Library/Application Support/FastSampler/ on macOS. macOS builds are signed ad hoc rather than notarised, so Gatekeeper will ask; the Homebrew cask clears the quarantine flag for you.

A sampler that starts in a moment.