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Try the Sandbox

The Sandbox is a public EvidentSource instance running at sandbox.evidentsource.com. This page walks you from zero to your first command, read, and event trace — no install required.

1. Get an API endpoint

Section titled “1. Get an API endpoint”

The Sandbox exposes the full EvidentSource API surface at:

  • REST: https://sandbox.evidentsource.com
  • gRPC: grpcs://sandbox.evidentsource.com:50051
  • MCP (for AI agents): https://sandbox.evidentsource.com/mcp

You don’t need an account or API key to use the Sandbox. (See the notice above.)

2. Issue your first command

Section titled “2. Issue your first command”

The Sandbox comes pre-loaded with a TodoMVC example — a simple app with commands like CreateTodo, CompleteTodo, and state views like todo-list.

Pick your language and send a command:

Terminal window
# REST — using curl
curl -X POST https://sandbox.evidentsource.com/v1/commands \
  -H "Content-Type: application/json" \
  -d '{
    "database": "todomvc",
    "command": {
      "type": "CreateTodo",
      "subject": "todo-123",
      "data": { "title": "Try EvidentSource" }
    }
  }'

You’ll get back an acknowledgement with the revision number of the appended event.

3. Read a state view

Section titled “3. Read a state view”

State views are materialized projections — evolve functions have folded the event log into queryable state. Read one:

Terminal window
curl https://sandbox.evidentsource.com/v1/state-views/todo-list?database=todomvc

You should see your todo in the list.

4. Query the event trace

Section titled “4. Query the event trace”

Every command produces events. Every event is queryable by stream, subject, and type — bi-temporally.

Terminal window
# All events for subject "todo-123"
curl "https://sandbox.evidentsource.com/v1/events?database=todomvc&subject=todo-123"

This is the decision trace — the full record of what happened, when, and in response to what command. It’s the thing that makes EvidentSource-backed systems auditable by default and AI-friendly by design.

5. Use an SDK

Section titled “5. Use an SDK”

The SDKs give you typed clients, codegen for commands and state views, and the decide/evolve scaffolding for writing your own components.

See Connecting with an SDK for Rust, Go, TypeScript, Python, and .NET examples.

Next steps

Section titled “Next steps”