Give any the abilityto reason.

Arbiter is an open-source reasoning runtime for software, devices, and machines. Turn events into supervised, stateful actions with durable memory and a complete live execution stream.

Open sourceInstall locally GitHubView repository

POST /v1/events · source=edge/rack-04

type=sensor.temperature.threshold · value=84.6°C

event_receivedevt_8s3z · authenticated device

route_matchsensor.* → facilities

stream_startfacilities · depth 1

facilities: checking thermal history and response policy

tool_call/mem read rack-04 thermal history

tool_output3 prior events · cooling policy v3

tool_call/parallel diagnostics, operations

tool_output2 specialists started

delegatediagnostics, operations

stream_startdiagnostics · depth 2

tool_call/exec read_sensors --zone rack-04

tool_outputinlet=31.2 · cpu=84.6 · fan=61%

tool_call/exec inspect_processes --top 5

tool_outputinference-worker using 93% GPU

diagnostics: sustained compute load is driving the thermal spike

stream_startoperations · depth 2

Route each decision to the right model

Claude Opus 4.7
Claude Sonnet 4.6
Claude Haiku 4.5
GPT-5.5
GPT-5.4
GPT-5.4 mini
o4-mini
Gemini 3.1 Pro
Gemini 3 Flash
Gemini 3.1 Flash-Lite
Nano Banana 2
Nano Banana Pro
nemotron3
qwen3.6
kimi-k2.6
granite4.1

01Software

Reason over every event.

Turn webhooks, queues, incidents, and application state into decisions made with durable context — not another stateless model call.

02Hardware

Give devices a reasoning layer.

Connect sensors, robots, edge computers, and embedded systems through HTTP or a lightweight bridge. Keep models and credentials off the device.

03Control

Let it act—with supervision.

Route work to specialized agents, constrain the tools they can use, and enforce advisor gates before consequential actions leave the runtime.

On the wire

From event to supervised action.

Post an event from a service, sensor, or device. Arbiter routes it to the right agent, supplies operational memory, executes permitted tools, and streams every decision back as structured SSE.

See the event catalog

How it differs

The reasoning layer, already handled.

Capability	Arbiter Runtime	Model APIs	Agent frameworks	DIY
Route hardware and software events	Yes	No	custom code	build it
Structured stream of every agent step	Yes	tokens only	varies	build it
Advisor gates at the runtime layer	Yes	No	custom code	build it
Memory and artifacts across turns	Yes	No	bring storage	build it
Local, cloud, or hybrid model routing	Yes	provider only	varies	build it
One binary for TUI, CLI, and HTTP	Yes	No	library only	build it

Open API

Connect anything over HTTP.

Send structured events from an application, webhook, edge computer, or hardware bridge. Arbiter routes each event by type and returns the full reasoning and action trace as a live stream.

Read the event API docs

POST /v1/eventsSSE · OpenAPI 3.1

curl -N http://127.0.0.1:8080/v1/events \
  -H "Authorization: Bearer $ARBITER_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "type": "sensor.temperature.threshold",
    "source": "edge/rack-04",
    "payload": { "celsius": 84.6 }
  }'

Get started

Add reasoning to what you are building.

Run Arbiter locally, define the agents and capabilities your system needs, then connect your first event source.

Install locally

Give any systemthe abilityto reason.