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.

Get early access View on GitHub →
75%of APIs non-conformant in production
$15kcost per minute of downtime
5 minpolling on Pro plan
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
Monitor any API with an OpenAPI spec — including ones you don't own
Stripe Twilio Plaid GitHub SendGrid Shopify Brex + 40 more
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.
🚨
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 Plaid and know the moment a provider changes their API — before it breaks your integration.
⚙️
CI/CD integration
JSON output mode with exit code 1 on breaking violations. Drop it into any GitHub Actions or GitLab CI pipeline to block deploys when your API has drifted.
🔑
Auth support
Bearer tokens, API keys, HTTP Basic, and OAuth2 — all supported via an encrypted credentials store. Credentials are never logged or stored in plain text.
Violation types

Nine classes of drift, detected automatically

DriftSignal classifies every violation by severity — breaking violations that cause immediate failures, and drift violations that signal future risk.

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
  • Open source CLI
Most popular
Team
$149/month
For engineering teams monitoring production APIs and third-party providers.
  • 20 API watches
  • 15-minute polling
  • Slack + webhook alerts
  • 90-day violation history
  • CI/CD integration
  • Third-party library (50+ APIs)
  • 5 team members
Pro
$499/month
For teams where API reliability is mission-critical and monitoring is non-negotiable.
  • Unlimited watches
  • 5-minute polling
  • PagerDuty integration
  • Unlimited history + CSV export
  • SSO + audit log
  • SLA guarantee
  • Priority support

Get early access

DriftSignal launches June 30, 2026. Join the list and get notified the day it's live — plus first month free on any paid plan.

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