Flaky API tests are one of the biggest killers of trust in automation. They pass on one run, fail on the next, and trigger the same internal debate every time: “Is something actually broken, or is our test suite behaving odd again?”
We’ve seen it a thousand times. Whenever a CI/CD pipeline turns red, it’s because a critical API test has failed. The developers stop their work, and everyone tries to figure out what’s broken. Then, someone re-runs the process, and… it passes.
Why? Because once you and your team lose confidence, they stop taking failures seriously—and your CI pipeline becomes and dead end instead of a gate.
What exactly is a flaky API test?
A flaky API test is one that behaves inconsistently under the same conditions—same code, same environment, same inputs. The key factor to notice here is non-determinism. You can re-run it five times and get a mix of passes and failures. This isn’t bad test writing; it’s usually a signal that something deeper is unstable—timing, dependency calls, shared state, or the environment itself.
Understanding this helps teams shift from blaming QA to fixing systemic issues in API stability.
Why are flaky API tests such a big deal in CI/CD?
CI/CD pipelines rely on fast, trustworthy feedback loops. Flaky API tests break that trust. They slow delivery, cause you to re-run them, hides real issues, and pushes developers toward shortcuts like adding retries just to get a green build. Eventually, people stop paying attention to failures altogether—creating a dangerous “green means nothing” tendency.
“Flakiness is one of the top silent blockers of fast-paced engineering teams.”
How to identify if a failed test is flaky or a real defect?
Test diagnosis as a process, not a guess. Teams typically check:
• Does the test pass on immediate re-run?
• Are related API tests also failing?
• Did the environment show latency spikes?
• Has this test shown inconsistent behavior before?
Step 1: Capture the Failure Context Immediately
• Record:
• Endpoint, payload, headers
• Environment (dev/stage, build number, commit SHA)
• Timestamps, logs, and any upstream/downstream calls
• In qAPI, ensure each run stores full request/response, environment, and log metadata for every test so you always have a forensic snapshot of failures.
Step 2: Re-run the Same Test in Isolation
• Re-run the exact same test:
• Same environment and with the same payload and preconditions
• Do this in a way that the execution path matches the original:
• If it fails consistently then there’s strong signal of a real defect.
• If it passes on immediate re-run then we can suspect flakiness.
Step 3: Check the Test’s History and Stability
• Look at the past runs for this specific test:
• Has it been green for weeks and suddenly started failing?
• Has it flipped pass/fail multiple times across recent builds?
In qAPI, use trend/historic test reports and there are two ways to direct this towards:
• If the failure starts exactly at a specific commit/build, lean toward real defect.
• If the same test has intermittent failures across unchanged code, mark it as a flakiness candidate.
Step 4: Correlate With Related Tests and Endpoints
• Check whether:
• Other tests hitting the same endpoint or business flow also failed.
• Only this single test failed while others touching the same API stayed green.
• In qAPI, you can filter by:
• Endpoint (e.g., /orders/create)
• Tag/feature (e.g., “checkout”, “auth”)
Step 5: Inspect Environment and Dependencies
• Validate:
• Was there an outage or spike in latency on the backend or a thirdparty service?
• Were deployments happening during the run?
• Any DB, cache, or network issues?
• In qAPI, correlate test failure timestamps with:
• API performance metrics
• Error rate charts
Step 6: Analyze Test Design for Flakiness Triggers
Review the failing test itself to see if it:
• Does it:
• Depends on shared or preexisting data?
• Uses fixed waits (sleep) instead of polling/conditions?
• Assumes ordering of records or timing of async operations?
Step 7: Try Reproducing Locally or in a Controlled Environment
• Run the same test:
• Locally (via CLI/qAPI agent) and in CI
• Against the same environment or new.
• Compare the results to see:
• If it fails everywhere with the same behavior then it’s a real defect.
• If it fails only in specific pipeline/agent or at random then it’s flakiness or environment issue.
Step 8: Decide and Tag: Flaky vs Real Defect
Make an clear call and record it:
• As real defect when:
• Failure is reproducible on repeated runs.
• It correlates with a recent code/config change.
• Related tests for the same flow are also failing.
• Classify as flaky when:
• Re-runs intermittently pass.
• History shows pass/fail flips with no relevant change.
• Root cause factors are timing/data/env rather than logic.
In qAPI you can
• Tag the test (e.g., flaky, env-dependent, investigate).
• Move confirmed flaky tests into a “quarantine” suite so they don’t block merges but still run for data.
• Create a new testing environment directly from qAPI to track fixing the flakiness.
Step 9: Feed the Learning Back Into Test & API Design
Once you’ve identified a test as flaky:
• Fix root causes, not just symptoms by:
• Improving test data isolation.
• Replacing hard coding time delays with condition-based waits.
• Strengthen environment stability or add mocks where needed.
• For real defects:
• Link qAPI’s failed run, logs, and payloads to a ticket so devs have complete context.
What are the most common causes of flaky API tests?
The majority of API flakiness falls into predictable categories:
• Timing issues: relying on fixed waits instead of real conditions.
• Shared or dirty data: test accounts reused across suites.
• Unstable staging environments: multiple teams deploying simultaneously.
• Third-party API calls: rate limits, sandbox inconsistencies.
• Race conditions: async operations not completing in time.
Once you classify failures into these buckets, you can start projecting patterns—and based on that teams can solve the root cause.
Can we detect flaky API tests proactively instead of waiting for failures?
Yes—teams worldwide are doing it. Here’s a short summary of their detection techinques:
• Running critical tests multiple times and measuring variance.
• Tracking historical pass/fail trends per API.
• Flagging tests with inconsistent outcomes.
• Creating a “Top Flaky API Tests” report weekly.
Flakiness becomes manageable when it is visible, measured, and reviewed—just like any other quality metric.
How do we design API tests that are less flaky from day one?
Stable API automation comes from building tests that are:
• Deterministic: same input, same output.
• Data-independent: each test owns and cleans up its state.
• Condition-based: waiting for the system to reflect the correct state.
• Reproducible: no hidden randomness or external surprises.
• API-layer focused: validating contracts and flows, not UI noise.
A good rule that we follow: A test should run in any environment, on any machine, and give the same result every time.
How much flakiness is actually caused by environment issues?
Far more than most teams admit. Shared staging environments are notorious for:
• Partial deployments
• Old configuration
• DB resets
• Parallel loads from other teams
• Third-party dependency failures
You can curate the perfect automation strategy and still get flaky results in a noisy environment. This is why modern engineering cultures prefer dedicated environments that are lean, isolated, and consistent.
When the environment stabilizes, the flakiness rate drops dramatically.