Tessera

Service contract coordination — stop breaking each other's APIs.

Tessera helps teams coordinate schema changes across service boundaries. When a producer wants to make a breaking API change, consumers are notified and must acknowledge before the change goes live.

Why Tessera?

Teams face a common problem: breaking changes break other teams' services. Dependencies between services are invisible unless someone manually documents them.

• A team removes a field from their REST API
• Three other services that depend on that field break in production
• The team that made the change only finds out when another team's oncall pages at 2 AM
• Everyone scrambles to fix it

Tessera solves this by making dependencies explicit and breaking changes coordinated:

1. Producers publish contracts - JSON Schema definitions of their API endpoints, gRPC methods, GraphQL operations, or data models
2. Consumers register dependencies - Teams declare which contracts they depend on
3. Breaking changes require acknowledgment - Before a breaking change goes live, all consumers must acknowledge

Key Features

• Schema Diffing - Automatically detect breaking vs non-breaking changes across any JSON Schema source
• Consumer Registration - Track who depends on what
• Proposal Workflow - Coordinate breaking changes across teams
• Sync Adapters - Import contracts from OpenAPI specs, GraphQL introspection, gRPC/protobuf definitions, and dbt manifests
• Audit Logging - Track all contract changes and data quality events
• Web UI - Visual interface for managing contracts and proposals

Quick Example

import httpx

# Publish a contract for your asset
response = httpx.post(
    "http://localhost:8000/api/v1/assets/my-asset-id/contracts",
    params={"published_by": "your-team-id"},
    json={
        "schema": {
            "type": "object",
            "properties": {
                "user_id": {"type": "integer"},
                "email": {"type": "string"},
                "created_at": {"type": "string", "format": "date-time"}
            },
            "required": ["user_id", "email"]
        },
        "compatibility_mode": "backward"
    }
)

If you later try to remove email (a breaking change), Tessera will:

1. Create a Proposal instead of publishing immediately
2. Notify all registered consumers
3. Wait for acknowledgments before allowing the change

Getting Started

• Quickstart

  ---

  Get up and running in 5 minutes with Docker

  Quickstart

• Installation

  ---

  Install Tessera in your environment

  Installation

• AI Agent Integration

  ---

  Give your AI agents contract-aware guardrails

  Agent Guide

• Concepts

  ---

  Understand how Tessera works

  Concepts

• API Reference

  ---

  Complete API documentation

  API Reference

Architecture

┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐  ┌─────────────────┐
│  OpenAPI Spec   │  │ GraphQL Schema  │  │  gRPC/Protobuf  │  │  dbt Manifest   │
└────────┬────────┘  └────────┬────────┘  └────────┬────────┘  └────────┬────────┘
         │                    │                    │                    │
         └────────────────────┼────────────────────┼────────────────────┘
                              ▼
                    ┌─────────────────┐
                    │    Tessera      │
                    │    Server       │
                    │  (JSON Schema)  │
                    └────────┬────────┘
                             │
        ┌────────────────────┼────────────────────┐
        │                    │                    │
        ▼                    ▼                    ▼
┌───────────────┐  ┌─────────────────┐  ┌───────────────┐
│   Producer    │  │    Consumer     │  │   Consumer    │
│   Team A      │  │    Team B       │  │   Team C      │
└───────────────┘  └─────────────────┘  └───────────────┘

License

Tessera is open source under the Apache License 2.0.