API contract drift monitoring

Stop finding out about API failures from your customers.

DriftSignal continuously monitors your APIs against their OpenAPI specs and alerts your team the moment they diverge — before anyone notices.

Start for free

75%of APIs non-conformant in production

$15kcost per minute of downtime

5 minpolling on Pro plan

Coming soon Active contract testing and write-method (POST/PUT/DELETE) checks, not just monitoring.

stripe.com/openapi.json

● 3 violations

BREAKING GET /v1/customers MISSING_REQUIRED_FIELD

DRIFT GET /v1/charges UNDOCUMENTED_FIELD

DRIFT GET /v1/balance TYPE_MISMATCH

CLEAN GET /v1/prices all clear

CLEAN GET /v1/invoices all clear

How it works

Continuous monitoring, zero infrastructure

No agents. No sidecars. No code changes. Point DriftSignal at your OpenAPI spec and it handles the rest.

📋

Connect your spec

Paste the URL to your OpenAPI or Swagger file. DriftSignal parses it, resolves all references, and builds a complete endpoint map. Supports OpenAPI 3.x and Swagger 2.0.

🔁

Continuous polling

Every 5–60 minutes (depending on your plan), DriftSignal calls your live API endpoints and validates every response against the declared schema — recursively. Currently GET (read) endpoints only — write-method monitoring is on the roadmap.

🚨

Instant alerts

The moment a response diverges from the spec — missing field, wrong type, undocumented value — your team is notified via Slack, email, webhook, or PagerDuty.

🌐

Third-party API monitoring

Monitor APIs you don't control. Point DriftSignal at Stripe, Twilio, or GitHub and know the moment a provider changes their API — before it breaks your integration.

⚙️

CI/CD integration

A drop-in check script that runs a DriftSignal scan from your pipeline and fails the build (exit code 1) on breaking violations. Works with GitHub Actions, GitLab CI, or any shell pipeline — block deploys when your API has drifted from its spec.

🔑

Auth support

Bearer tokens, API keys, and HTTP Basic — all supported via an encrypted credentials store. Credentials are never logged or stored in plain text.

Violation types

Every kind of drift, detected automatically

DriftSignal classifies every violation by severity — breaking violations that cause immediate failures, drift that signals future risk, and warnings for lower-priority deviations.

Code Severity What it means

MISSING_REQUIRED_FIELD Breaking Required field absent from response

TYPE_MISMATCH Breaking Wrong JSON type returned

UNEXPECTED_NULL Breaking Non-nullable field returned null

UNDOCUMENTED_STATUS_CODE Breaking Status code not in spec

UNDOCUMENTED_FIELD Drift Field in response not in spec

UNDOCUMENTED_ENUM_VALUE Drift Enum value outside documented set

FORMAT_MISMATCH Drift String doesn't match declared format

ARRAY_TOO_SHORT Drift Array below minItems

ARRAY_TOO_LONG Drift Array above maxItems

The research

API failures are expensive and invisible

75%

of production APIs don't conform to their own OpenAPI specification

APIContext 2024

$15k

cost per minute of enterprise downtime

Splunk + Oxford Economics 2026

47%

of enterprises: customers detect the outage before internal teams

Splunk + Oxford Economics 2026

60%

increase in global API downtime year over year

ITRS Uptrends 2025

Pricing

Simple, predictable pricing

No per-endpoint billing. No usage surprises. Cancel any time.

Developer

$0/month

For individuals evaluating DriftSignal or monitoring a small number of APIs.

3 API watches
Hourly polling
Email alerts
7-day violation history
OpenAPI 3.x + Swagger 2.0

Get started free

Stop finding out about API failures from your customers.

Continuous monitoring, zero infrastructure

Every kind of drift, detected automatically

API failures are expensive and invisible

Simple, predictable pricing

Stay in the loop