AI that runs on your Mac and PC.
Or anywhere you want.
Download open models from Hugging Face and run them privately, or connect free cloud models from Google, Groq and OpenRouter. One native app for Mac and Windows, with web search, images, a browser and your files built in.
Free and open source · macOS 14 or later on Apple Silicon · Windows 10 and 11 on x64 and ARM64 (ARM64 installer)
May is ideal: highs around 22 °C and little rain. Here's a budget plan:
Day 1 Alfama, the 28 tram and sunset at Miradouro da Graça.
Day 2 Belém, pastéis de nata and the LX Factory.
Day 3 Day trip to Sintra by train (€2.40 each way).
Runs today's best open models, plus free cloud models
Local when you want privacy. Cloud when you want power.
Switch between a model on your computer and a model in the cloud in the same chat. Your history, files and projects stay on your machine.
Private, on-device models
Run GGUF models with llama.cpp, or MLX on a Mac. On Windows, Synapse uses your NVIDIA, AMD or Intel graphics card. No account, no limits, and nothing leaves your computer.
Picked for your hardware
Synapse reads your chip, memory and graphics card and picks the best model and quantization that will actually run well.
Free cloud models
Sign in to Google AI Studio, Groq or OpenRouter, paste a free key, and use their models. Keys are stored in the macOS Keychain or Windows Credential Manager.
Projects, files and instructions
Group chats into projects with their own folder and instructions. Models can read your documents, write new files and show you the results right in the chat.
See your limits
Live rate limits from Groq and request counts for every provider, so you know how much free usage is left.
Know what runs before you download.
Every model is checked against your computer's memory, and on Windows against your graphics card's VRAM too. Pick a memory size to see what Synapse would suggest.
Give any model new abilities.
Turn capabilities on per chat, for local and cloud models alike. Anything that changes your computer asks you first.
Fast
Straight answers, no extra reasoning.
Normal
The model decides how long to think.
Think hard
Maximum reasoning budget, step by step.
Think harder
A second pass reviews and corrects the answer.
Your models, from the command line.
Chat with any model in Terminal or PowerShell, or point your editor and scripts at Synapse's local OpenAI-compatible server. Local and cloud models share one endpoint.
$ synapse models local/qwen3.5-4b · Q4_K_M google/gemini-3.8-flash groq/llama-3.3-70b-versatile $ synapse chat google/gemini-3.8-flash --think high › Write a haiku about unified memory Thinking… One pool for all thoughts, GPU and CPU share the same quiet sea. $ curl localhost:11435/v1/chat/completions \ -d '{"model":"local/qwen3.5-4b", …}'
Questions
Is Synapse free?
Yes. Synapse is free and open source under the MIT license. Local models cost nothing to run. Cloud providers like Google AI Studio and Groq have free tiers; Synapse shows how much you've used.
Which computers are supported?
Macs with Apple Silicon running macOS 14 or later, and PCs running Windows 10 (1809) or later, on x64 or ARM64. On Windows, Synapse uses your NVIDIA (CUDA) or AMD and Intel (Vulkan) graphics card when it has one, and the CPU otherwise. 8 GB of memory runs small models well; 16 GB or more opens up larger, smarter ones.
Does my data leave my computer?
With local models, no: everything runs on your computer. With cloud models, your messages go to the provider you chose. Chats, projects and files are always stored locally.
Can the AI control my computer?
Only if you turn on Computer Access or Browser for a chat. Commands, AppleScript, PowerShell and form submissions ask for your approval, and the browser never types passwords.
macOS says it can't open Synapse. What do I do?
Open Synapse.dmg and drag Synapse into Applications. On first launch, if macOS blocks it, open System Settings › Privacy & Security and click Open Anyway. You only need to do this once.
Windows SmartScreen warns about Synapse. What do I do?
Synapse isn't code-signed yet, so SmartScreen may show a warning. Click More info › Run anyway. The installer needs no admin rights. If the WebView2 Runtime is missing (it's built into Windows 11), Synapse offers to download it. Prefer no installer? Unzip the portable zip from Releases and run Synapse.exe.
Where do the models come from?
Local models download straight from Hugging Face. You can also search the whole Hugging Face catalog for any GGUF model, or MLX model on a Mac.
Start running AI on your computer.
Free, private, and open source.