What is integration testing?

Integration testing checks that separate parts of a system work correctly together: modules inside your product, your product and third-party services, or several business systems. It finds the problems that only appear when data and requests pass from one part to another.

What is system integration testing (SIT)?

SIT is a planned test of the whole system with all its real connections, usually in a production-like environment. It follows complete business processes across every system involved and normally comes before user acceptance testing and go-live.

How is integration testing different from unit and end-to-end testing?

Unit tests check one small piece of code on its own. Integration tests check how pieces work together. End-to-end tests follow a complete user journey through the whole product. Integration testing sits in the middle and is where most data and interface problems are found.

How is this different from your API testing service?

API testing focuses on the API itself: its endpoints, security, performance and contract. Integration testing focuses on how your systems and partners work together end to end, including data flows, events, files and business processes. Many teams use both.

Which third-party integrations do you test?

Common ones include payment providers, CRM and marketing tools such as Salesforce and HubSpot, ERP and accounting systems, shipping and logistics services, identity providers and analytics. We test whatever your product connects to.

What if a partner has no sandbox or test environment?

We simulate it. Mock services, stubs and service virtualisation let us test normal, slow and failing responses, and we check the mocks against the real behaviour whenever we can.

Do you test webhooks and message queues?

Yes. We test signatures, retries, duplicate and out-of-order deliveries, dead-letter queues and what happens when the receiving system is slow or offline.

Can you test data migrations and ETL?

Yes. We check field mapping, record counts, totals and reconciliation from source to target, including dates, time zones, currencies and special characters.

Do you test SSO and identity integrations?

Yes. We test OAuth, OpenID Connect and SAML with providers such as Okta, Azure AD / Entra ID and Google, including role mapping, token refresh, logout and session expiry.

Can you work with SAP, Salesforce and other enterprise systems?

Yes. We test integrations with enterprise and legacy systems, and agree test plans and test data with the teams who own each system so nothing is changed without permission.

Can integration tests be automated?

Many can. Stable integration checks run well in CI using tools such as Postman with Newman, REST Assured, Pact and Playwright. New or fast-changing integrations are often tested by hand first.

An integration map, an integration test plan, test cases, bug reports traced to the interface that caused them, an SIT summary with open risks, and automated suites where agreed.

What do you need from us to start?

A list of the systems you connect to, access to test or sandbox environments, test accounts and a walkthrough of the business processes that cross those systems.

How do we get started?

Book a call or send the form on this page. We start with a free one-week proof of concept: we map your integrations and test the riskiest one end to end.

Integration Testing Services

Your product is only as reliable as its weakest connection: a payment provider, a CRM sync, a message queue or a file that arrives an hour late.

We test how your modules, systems and third-party services work together, end to end. We follow your data across every hand-off, try the failures that happen in real life, and trace each defect to the interface that caused it.

Get in touch Map your integrations

Modules, systems and partners
SIT sign-off
Manual or automated
Free one-week POC

What we do

Component integrationInside your product System integration testingEnd to end Third-party integrationsPayments, CRM, ERP, shipping Webhooks & queuesAsynchronous Data flow & ETLData in motion Contract testingBetween services SSO & identityOAuth, SAML, OIDC Enterprise systemsSAP, Salesforce and more Mocks & virtualisationWhen the real thing isn’t available Automated suitesEvery build

[ Why integration testing ]

Most serious bugs live between systems, not inside them

Each team tests its own part, and each part passes. Then a customer pays, the order never reaches the warehouse, and nobody’s tests failed. Integration problems hide in the hand-offs: a renamed field, a token that expires overnight, a webhook sent twice, a file in the wrong format. We test those hand-offs on purpose, with real data and real failures, so they don’t surprise you after go-live.

Testing the API itself? See API testing services →

Fewer go-live surprises

Systems tested together, not just one by one, before real users and data depend on them.

Clean data everywhere

Records, totals and statuses checked from where they start to where they end up.

Resilient to partner failures

Your product tested against slow, failing and changing third parties.

Faster root cause

Each defect traced to the system or interface that caused it.

[ What we test ]

Ten kinds of integration, tested end to end

From two modules inside your product to a chain of partners and enterprise systems. Each one lists what we test, when you need it and the problem it prevents.

Component & module integration

Inside your product

We test how the parts of your own product work together: the screens, services, database and background jobs, before they meet the outside world.

What we test

Data passed correctly between modules and layers
Front end, back end and database agree on every field
Background jobs, queues and scheduled tasks
Errors in one module handled by the next

When you need it

As soon as two modules can talk, and on every release after.

The problem it preventsFeatures that work alone but fail together

System integration testing (SIT)

End to end

A planned test of your whole system with all its real connections, in an environment as close to production as you have.

What we test

Business processes followed across every system involved
Integration test plan and entry and exit criteria
Defects traced to the system or interface that caused them
SIT sign-off before UAT or go-live

When you need it

Before UAT, go-live and any major system change.

The problem it preventsA go-live where the systems each work, but not with each other

Third-party integrations

Payments, CRM, ERP, shipping

The services you depend on but don’t control. We test how your product behaves when they work, when they are slow and when they fail.

What we test

Payments, refunds and payouts with Stripe, PayPal and others
CRM and marketing sync with Salesforce or HubSpot
ERP, accounting and shipping updates
Rate limits, timeouts, retries and provider outages

When you need it

Before launching an integration and whenever a provider changes its API.

The problem it preventsOrders, payments or records lost between systems

Webhooks, events & message queues

Asynchronous

Systems that talk through webhooks and queues fail quietly. We make those failures visible.

What we test

Webhook signatures, retries and duplicate deliveries
Messages in Kafka, RabbitMQ or SQS delivered once and in order
Dead-letter queues and failed consumers
What happens when the receiver is slow or offline

When you need it

For any event-driven feature, and after changes to message formats.

The problem it preventsEvents processed twice, out of order or not at all

Data flow & ETL between systems

Data in motion

We follow your data from where it is created to every place it ends up, and check that it arrives complete and correct.

What we test

Field mapping and format changes between systems
Batch jobs, file transfers and ETL pipelines
Record counts, totals and reconciliation
Dates, time zones, currencies and special characters

When you need it

For migrations, reporting projects and new data feeds.

The problem it preventsReports and dashboards built on wrong or missing data

Microservices & contract testing

Between services

Learn more

Contracts make sure one team’s change doesn’t silently break another’s service. We set them up and keep them running.

What we test

Consumer and provider contracts with Pact
Breaking changes caught before merge
Service-to-service flows across the full journey
Behaviour when one service is down or slow

When you need it

When several teams own different services.

The problem it preventsA small change in one service breaking three others. For API-level detail, see our API testing.

SSO & identity

OAuth, SAML, OIDC

Sign-in is the one integration every user touches. We test it across identity providers, roles and edge cases.

What we test

SSO with Okta, Azure AD / Entra ID, Google and others
OAuth and OpenID Connect token flows and refresh
SAML assertions, attributes and role mapping
Account linking, logout and session expiry

When you need it

When adding SSO, a new identity provider or new roles.

The problem it preventsUsers locked out, or given access they should not have

Legacy & enterprise systems

SAP, Salesforce and more

Older and enterprise systems often hold the data that matters most. We test your connections to them carefully, with your system owners.

What we test

Integrations with SAP, Salesforce, Microsoft Dynamics and similar
SOAP services, file drops and older interfaces
Master data, customers, products and orders kept in step
Test plans agreed with the teams who own each system

When you need it

For ERP and CRM projects, upgrades and replacements.

The problem it preventsAn upgrade that breaks a connection nobody documented

Mocks, stubs & service virtualisation

When the real thing isn’t available

When a partner has no sandbox, or a system is expensive or slow to use, we simulate it so testing doesn’t stop.

What we test

Mock services with WireMock for third-party APIs
Disposable test databases and queues with Testcontainers
Error, timeout and edge-case responses on demand
Mocks checked against real behaviour regularly

When you need it

When sandboxes are missing, unstable or limited.

The problem it preventsTesting blocked for days waiting for a partner

Automated integration suites in CI

Every build

View service

Integration tests that run in your pipeline on every change, so broken connections are caught before they reach staging.

What we test

Suites in Postman with Newman, REST Assured and Playwright
Contract checks with Pact on every pull request
Runs in GitHub Actions, Jenkins or your CI
Clear reports showing which integration failed

When you need it

Once your integrations are stable enough to automate.

The problem it preventsBroken integrations found days after the change that caused them

[ Where integrations fail ]

Six ways integrations break in real life

We test each one on purpose. And every integration test case we write looks like the one on the right: a real flow, a real failure and every system checked.

Failure	Real example	How we test it
Data mapping	A “state” field saved as “ON” in one system and “Ontario” in another	Field-by-field mapping checks and reconciliation
Timing & order	The shipping update arrives before the order exists	Events sent out of order, delayed and replayed
Auth & tokens	Integration stops overnight when a token expires	Token expiry, refresh and revoked credentials
Partial failure	Payment taken, order never created	Failures injected mid-flow; retries and rollback checked
Duplicates	A webhook retried and the customer charged twice	Duplicate deliveries and idempotency checks
Versions & contracts	A partner adds a field and your import breaks	Contract tests and schema change checks

Sample integration test caseFailure scenario

Flow: Checkout → payment provider → order service → ERP
Scenario: Payment succeeds, ERP is down for 10 minutes
Steps: 1. Place order with a test card 2. Block the ERP endpoint 3. Restore it after 10 minutes
Expected: Order kept as “paid, pending ERP”, sent automatically when ERP returns, no duplicate
Checks: Order status, ERP record, payment record, retry log, customer email
Data: Totals, tax and currency match in all three systems

Example only. Real cases are written for your systems.

[ How we work ]

Six steps from integration map to SIT sign-off

You see every connection we test, in the order that matters to your business. Every map, plan and report belongs to you.

Step 1 of 6
Map your integrations

Every system, connection, data flow and owner, drawn on one page with your team.

You getIntegration map
Step 2 of 6
Plan by risk

Integration points ordered by business impact and data sensitivity.

You getIntegration test plan
Step 3 of 6
Prepare environments

Sandboxes, test accounts, test data, and mocks where real systems aren’t available.

You getEnvironment checklistMock services
Step 4 of 6
Test end to end

Each integration, then full business flows across systems, including failures.

You getBug reports traced to the interface
Step 5 of 6
Automate what repeats

Stable integration checks moved into your CI pipeline.

You getAutomated integration suite
Step 6 of 6
Sign off and hand over

SIT summary, open risks and what to monitor in production.

You getSIT sign-offMonitoring checklist

Free one-week POCWe map your integrations and test the riskiest one end to end, so you can judge our work first.
Agreed with system ownersTest data and access agreed with the teams who own each system before we touch it.
NDA before accessWe sign your NDA first and use sandboxes, test accounts and test data by default.

[ Tools ]