Optic — the YC-backed, open-source API diff tool — is gone.
The GitHub repo was archived on January 12, 2026, following Atlassian's acquisition in April 2024 and months of subsequent inactivity (last release: August 2025). With only 91 forks and no meaningful community continuation, the project is effectively dead. Despite expectations that the technology would be folded into Atlassian Compass, there's no evidence of integration — Compass remains focused on component catalogs and DORA metrics, not API drift detection. The useoptic.com domain no longer resolves.
If you relied on Optic for catching API schema changes, you need a replacement. Here's what the landscape looks like in 2026.
What Optic did well
Optic solved a real problem: it compared OpenAPI spec versions and caught breaking changes before they shipped. You'd run optic diff in CI, and it would tell you if your new spec introduced incompatible changes — removed fields, changed types, new required parameters.
The approach was sound. The limitation was that it only worked with spec files. If your spec was outdated (common), or if you were consuming a third-party API you didn't control (very common), Optic couldn't help.
The gap Optic left
Optic's shutdown leaves two distinct gaps:
1. Spec-to-spec diffing in CI — Comparing your OpenAPI spec versions during development.
2. Live drift detection — Monitoring whether your actual API responses match what you expect, in staging or production.
Most teams need the second one more than the first, but Optic only did the first.
Alternatives for spec-to-spec diffing
If you specifically need Optic's CI/CD spec comparison workflow:
oasdiff (open source)
The most direct Optic replacement for spec-to-spec diffing. 1,100+ GitHub stars, actively maintained.
- Compares two OpenAPI spec files
- 300+ breaking change detection rules
- GitHub Action available for CI integration
- Free, open source (Apache 2.0)
- CLI + web diff calculator at oasdiff.com
Best for: Teams with up-to-date OpenAPI specs who want CI-time validation. If this was your Optic workflow, oasdiff is a drop-in replacement.
PactFlow Drift (new, March 2026)
CLI tool from PactFlow that auto-generates test suites from OpenAPI specs using AI.
- Verifies API implementations conform to their OpenAPI definitions
- Runs in CI pipelines alongside PactFlow's existing contract testing
- Leverages PactFlow's strong brand in the contract testing space
- Pricing TBD
Best for: Teams already in the PactFlow ecosystem who want spec validation integrated into their existing contract testing workflow. CI-only — not continuous monitoring.
Bump.sh
API documentation platform with built-in change detection.
- Tracks spec changes across versions
- Generates changelogs automatically
- API hub for internal/external consumers
- Starting at $50/month
Best for: Teams that want spec hosting + change tracking in one tool.
Alternatives for live drift detection
If your real problem is "my API changed in production and nobody told me":
FlareCanary
Live API schema drift monitoring — no spec required.
- Polls your endpoints on a schedule and compares responses against a learned baseline or your OpenAPI spec
- Severity classification: breaking vs. warning vs. informational
- Multi-sample baseline learning to reduce false positives from conditional fields
- MCP server monitoring for AI agent tool schemas
- Email and webhook alerts with exact diff of what changed
- Free tier: 5 endpoints, daily checks. Paid from $19/month.
Best for: Teams monitoring third-party APIs they don't control, or catching drift between spec and reality. This is the gap Optic couldn't fill — live monitoring of actual responses, not just spec file comparisons.
[Full disclosure: I built FlareCanary.]
Treblle
API intelligence platform with observability and governance.
- Monitors your own APIs via SDK instrumentation
- Request/response logging with analytics
- Starting at $25/month (free tier available)
Best for: Teams wanting full API observability for APIs they own. Does not monitor external/third-party APIs.
Other options worth knowing
API Drift Alert — The other dedicated drift monitoring tool. Severity-aware alert routing and PagerDuty integration, starting at $149/month (7-day trial, no free tier). Worth evaluating if you need enterprise alerting pipelines.
APIShift — General API monitoring platform with schema drift as one feature. Free tier (5 APIs, hourly checks), Pro at $29/month. Broader monitoring suite but shallower on drift-specific detection.
Rumbliq — Full monitoring platform (uptime, SSL, DNS, schema drift). Generous free tier (25 monitors). Good if you want a general monitoring dashboard with basic drift detection included.
Why Optic's approach wasn't enough
The root problem with pure spec diffing is that it assumes the spec is the source of truth. In practice:
- Specs go stale. Developers change code and forget to update the spec.
- Third-party APIs don't give you specs. You get docs (maybe) and live responses.
- Runtime behavior diverges. A field that's always present in staging starts returning
nullin production under load.
Optic caught the first case (spec version drift) but not the second or third. The most dangerous API changes are the ones that happen without anyone updating a spec file.
Live monitoring — actually hitting the endpoint and comparing what comes back — catches all three cases.
What to do now
If you're migrating from Optic:
For CI spec validation: Switch to oasdiff. Open source, actively maintained, GitHub Action available.
For live monitoring: Try FlareCanary. Free tier, no spec required, catches drift between reality and expectations.
For both: Use oasdiff in CI + FlareCanary in staging/production. They're complementary — one validates your specs, the other validates your reality.
The API drift problem didn't go away when Optic did. The tools just need to match how the problem actually manifests — in production, silently, without anyone updating a spec file.
FlareCanary monitors REST APIs and MCP servers for schema drift. Free tier, no credit card. flarecanary.com
