Retry & Idempotency Contract Builder

Generate endpoint-level retry and idempotency contracts with deterministic test vectors and rollout guidance

{
  "contracts": [
    {
      "method": "GET",
      "path": "/v1/items",
      "criticality": "low",
      "idempotencyRequired": false,
      "retry": {
        "strategy": "exponential-jitter",
        "maxAttempts": 4,
        "baseDelayMs": 200,
        "maxDelayMs": 5000,
        "retryableStatusCodes": [
          408,
          425,
          429,
          500,
          502,
          503,
          504
        ]
      },
      "testVector": {
        "duplicateRequest": false,
        "replayWindowSec": 0
      }
    },
    {
      "method": "POST",
      "path": "/v1/orders",
      "criticality": "high",
      "idempotencyRequired": true,
      "retry": {
        "strategy": "exponential-jitter",
        "maxAttempts": 3,
        "baseDelayMs": 200,
        "maxDelayMs": 5000,
        "retryableStatusCodes": [
          408,
          425,
          429,
          500,
          502,
          503,
          504
        ]
      },
      "testVector": {
        "duplicateRequest": true,
        "replayWindowSec": 86400
      }
    },
    {
      "method": "PATCH",
      "path": "/v1/orders/{id}",
      "criticality": "high",
      "idempotencyRequired": true,
      "retry": {
        "strategy": "exponential-jitter",
        "maxAttempts": 3,
        "baseDelayMs": 200,
        "maxDelayMs": 5000,
        "retryableStatusCodes": [
          408,
          425,
          429,
          500,
          502,
          503,
          504
        ]
      },
      "testVector": {
        "duplicateRequest": true,
        "replayWindowSec": 86400
      }
    }
  ],
  "defaults": {
    "requestTimeoutMs": 10000,
    "retryBudgetPerMinute": 120,
    "backoffFormula": "min(maxDelayMs, baseDelayMs * 2^attempt) + random(0..baseDelayMs)"
  }
}

Updated October 2, 2026. Provided as is. Check the output before you rely on it in production.

How to use Retry & Idempotency Contract Builder

1

List API endpoints in JSON

Provide endpoint method and path pairs to define the surface where retry and idempotency policy needs to be generated.
2

Build reliability contracts

Run Build Contract to generate per-endpoint retry strategy, retryability rules, and idempotency requirements.
3

Review risky methods and safeguards

Check POST and other mutating methods for idempotency key requirements and confirm failure-mode handling guidance.
4

Convert output into implementation tasks

Apply contract output in API gateway, service middleware, and test suites to enforce consistent retry behavior.

Questions and answers

What is Retry & Idempotency Contract Builder?

An idempotency key lets a server recognize a retried request so it is not applied twice. This builder writes a contract per endpoint: keys required for POST and PATCH, exponential backoff with jitter (3 attempts, 4 for GET), retryable status codes, and a duplicate-request test vector.

Which endpoints should require idempotency keys?

State-changing operations like POST and PATCH usually require idempotency safeguards. The contract marks risky methods so you can enforce key handling consistently.

What retry strategy does it output?

The builder outputs an exponential backoff with jitter profile by default, including retryability guidance by status class and operational notes for safe recovery.

Does Retry & Idempotency Contract Builder store or send my data?

No. Contract generation runs in your browser and does not transmit endpoint definitions.

For AI agents: how to call this tool

Machine-readable contract, endpoints and examples. Humans can ignore this section.

Best Path For Builders

Browser workflow

Runs instantly in the browser with private local processing and copy/export-ready output.

Browser Workflow

This tool is optimized for instant in-browser execution with local data handling. Run it here and copy/export the output directly.

/retry-idempotency-contract-builder/

For automation planning, fetch the canonical contract at /api/tool/retry-idempotency-contract-builder.json.

Retry & Idempotency Contract Builder