Reason does the work. Synapse connects the agents doing it. Reason (reasonmachines.com) is an autonomous coding agent: give it a task and it returns a pull request with recordings, logs and a diff. Synapse is not an agent. It links the CLI agents already running on your machine so they read each other's recent conversation and can message each other. Synapse is MIT, needs no account and makes no network calls. Reason is proprietary and runs its agent loop in its cloud. They fit together: a Synapse-linked Claude Code or Codex agent can hand a task to Reason through Reason's MCP plugin.
At a glance
| Synapse | Reason | |
|---|---|---|
| What it is | Canvas and messaging layer for every agent on your machine, plus a desktop app in development | Autonomous coding agent: task in, pull request out |
| Layer | Connects agents you already run | Is the agent |
| License | MIT, open source | Proprietary (plugin connector repo is MIT) |
| Price | Free | No published price list; local use described as free on Product Hunt |
| Account | None | Workspace login (reason login) or REASON_API_KEY |
| Network | No network calls | Agent loop runs in Reason's cloud, even when commands run on your laptop |
| Where work runs | Wherever your agents already run | Your Mac, cloud Linux, cloud Mac or a registered machine |
| Live context links between running agents | Yes, directional, every prompt | No |
| Agent to agent messaging | Yes, any linked agents, across CLIs | One-way: Claude Code, Codex or Cursor can create a Reason session and read its result |
| Sees agents it did not launch | Yes, by process scan | No, only its own sessions |
| PRs, screen recordings, CI fixes, Slack, iOS | No | Yes |
Reason facts are from reasonmachines.com, its docs and its GitHub org, checked on 16 October 2026.
What Reason is
Reason is built by Reason Machines, a small San Francisco team (two people on its YC page) from Y Combinator's Spring 2026 batch. You connect a GitHub repo and hand Reason a task or an issue. It works in an isolated environment (your Mac, cloud Linux or cloud Mac) and returns a pull request with screen recordings, before and after screenshots, logs and a diff.
It also has web, Mac and iOS apps, a CLI for macOS, Linux and Windows, a Slack bot, an API, scheduled tasks and GitHub issue assignment. Large jobs are split across Reason's own parallel subagents.
Reason publishes benchmark and cost comparisons against Codex. These are vendor claims, not independently verified.
If you searched for the Ara coding agent: Reason is the product previously called Ara, which was described as a self-driving IDE. The old ara MCP endpoint is retired, and the current plugins connect to Reason.
What Synapse is
Synapse starts from a different problem. You have Claude Code in one terminal and Codex in another. One just learned something the other needs, and the only way it gets across is you copying text.
Synapse puts every live agent on your machine on one canvas, grouped by git repo. Drag from one agent to another and the second one sees what the first is doing. On each prompt, a hook injects what the linked agent said since last time, capped at 8,000 characters per link. Linked agents can also message each other through six MCP tools, a CLI and a skill, across vendors.
synapse link codex-api
synapse send codex-api "I'm sending the flaky test to Reason. Hold off on that file."
synapse inboxHow agents talk to each other in Reason and in Synapse
Reason:
- Inside Reason, big tasks are split across Reason's own internal subagents, not third-party CLIs.
- Between Reason and your local agents, the link is one-way delegation over MCP. Plugins for Claude Code, Codex and Cursor add commands such as
/reason-fix,/reason-buildand/reason-status. Your agent starts a Reason session asynchronously, checks its status and reads its result. - People steer a running session with
reason sendor by replying in a Slack thread.
We did not find a way, in the pages we read, for two independent local agents to share context or message each other.
Synapse:
- Links are live and directional. A link from A to B means B gets A's new conversation on every prompt until you remove it. Draw both ways for a pair.
- Any two linked agents can message each other, whichever CLI each runs in.
- Messages are pulled, not pushed. An idle agent does not wake up on a message.
So Reason gives your agent a powerful tool to call. Synapse gives your agents a way to know about each other.
Open source, accounts and privacy
Reason is proprietary; only docs and an MIT plugin connector are public. You sign in to a workspace in the browser, or use an API key for headless runs. Per its CLI README, the agent's model calls, planning, memory and tools run in Reason's cloud even when commands run on your laptop. Reason's homepage claims zero data retention and SOC 2; we have not checked these independently.
Synapse is MIT licensed, with a zero-dependency Node core and no account. Links and messages live in ~/.synapse, and Synapse makes no network calls.
Where Reason is ahead
- It does the work end to end. Isolated environments, a full desktop and browser per session, PRs with video and screenshots, review comments, CI fixes and the merge queue. Synapse has no PR flow, sandboxes or issue tracker integration.
- It goes where you go. Web, iOS, Slack and shared sessions, and cloud work continues after you close the laptop. Synapse is single-machine and macOS-first, and its multiplayer is in development.
- It competes on results. Reason publishes benchmark and cost numbers. Synapse is not an agent and does not compete on solve rate.
- It has backing. YC and NVIDIA Inception. Synapse is a young open-source project.
If you want one agent you can hand an issue to and get back a tested pull request, Reason is built for that and Synapse is not.
Using Synapse with Reason
- Install Synapse:
node install.mjs && npm start. - Install the Reason plugin in Claude Code or Codex and sign in to your Reason workspace.
- On the Synapse canvas, link your Claude Code agent and your Codex agent in both directions.
- When one of them hits a long, self-contained job, have it run
/reason-fixor/reason-buildto hand the task to Reason. - Ask that agent to
synapse sendthe PR link and a short summary to its linked peer.
Synapse keeps the local agents coordinated. Reason is one of the tools those agents call.
Who should pick which
- Pick Reason if you want an autonomous agent that turns tasks into evidence-backed pull requests, in the cloud or on your Mac, and you are fine with a login and a proprietary, cloud-run agent loop.
- Pick Synapse if your agents already do good work but do not know what each other are doing, you mix Claude, Codex and Gemini, or you want an MIT tool with no account and no network calls.
- Run both if you want local agents that share context and can also send big jobs to a cloud agent.
FAQ
Is Synapse a Reason alternative?
Not really. Reason is a coding agent that does tasks and opens pull requests. Synapse is not an agent; it connects the agents you already run. Many people would use both.
What is the Reason coding agent?
Reason, from Reason Machines (reasonmachines.com), is an autonomous coding agent. You give it a task or a GitHub issue, it works in an isolated environment on your Mac or in the cloud, and it returns a pull request with recordings, screenshots, logs and a diff.
Is Reason the same as the Ara coding agent?
Yes. Reason is the product previously called Ara, which was described as a self-driving IDE. The old Ara MCP endpoint is retired, and the current plugins for Claude Code, Codex and Cursor connect to Reason.
Can Claude Code hand tasks to Reason?
Yes. Reason's MCP plugin gives Claude Code, Codex and Cursor commands such as /reason-fix and /reason-status, so your agent can create a Reason session and read its result. It is one-way delegation. With Synapse, that same agent can also share context and messages with its linked local peers.
Is Reason open source or free?
Reason is proprietary. Only its documentation and a thin MIT-licensed plugin connector are public. It has no published price list, and its Product Hunt listing says you can start free on your own computer. Synapse is MIT licensed and free, with no paid tier.
Does Synapse need an account or send my code anywhere?
No. Synapse has no account, keeps links and messages in a local folder, reads transcripts from disk and makes no network calls.