Simulate real systems. Test without the dependency.
neoSim Simulate stands in for the third-party systems your application connects to. It reproduces their responses, webhooks, delays and failures, so your team can test any scenario, any time, without touching the live service.
simulators
architecture
by Neova
Your integrations depend on systems you don't control.
Identity providers, CRMs, messaging and security systems all belong to someone else. When one of them fails in front of a customer, your team is still accountable. Vendor sandboxes help, but they rarely let you test the moments that matter most.
Outages, resets and maintenance windows stall your pipeline.
Quotas and seat caps throttle the tests you need most.
Every run against a live service uses paid API quota.
Vendors update on their schedule, not your release plan.
Timeouts and failed callbacks never happen when you ask.
You can't push a live vendor to peak just to see what breaks.
Your application stays the same.
The system behind it is simulated.
neoSim takes the place of the external service during testing and responds exactly the way the real system would.
Unchanged
Same API calls, webhook handlers and SDKs you use in production.
Responds like the real system
Returns the responses, events, callbacks, delays and failures defined by your scenario.
Available on demand
Okta, Salesforce, Twilio, Milestone and 50+ more, on your terms.
Connect
Point your app at neoSim through the same APIs, webhooks and SDKs. No infrastructure changes.
Choose a scenario
Pick a scenario from the library or create your own, for success, a specific failure, an edge case or a full multi-step workflow.
See the outcome
Check the response, the callbacks that follow, and how your app handles them.
One control panel for every simulator.
Start a simulator, set it up like the real service and build the scenarios your integration has to survive.
Send real requests. Get realistic responses.
Call supported API actions the way your application would and see exactly what comes back, before you write integration code.
- Real status codes, payloads and timing
- Authentication flows and multiple API versions
- Learn how a service behaves in minutes
/api/v1/users?activate=trueSend{
"profile": {
"firstName": "Ava",
"lastName": "Patel",
"email": "ava.patel@acme.test"
}
}{
"id": "00u8f2k9sLx",
"status": "ACTIVE",
"created": "2026-09-28T10:14:03Z",
"profile": { "login": "ava.patel@acme.test" }
}Configure it like the real service.
Match each simulator to your production setup so your team tests against something that feels real.
- Authentication, API version and response delay
- Request limits, webhooks and platform events
- Isolated environments so parallel runs never collide
Build scenarios, including the ones that go wrong.
Use the form builder, the JSON editor, or simply describe what you want in plain language and let AI draft it.
- Chain requests, events, delays, failures and recovery
- No code or config files needed
- Save once, replay on every release
- TriggerPOST /incident → 201
- Notifywebhook incident.created · 3s
- FailPATCH /incident/{id} × 2 → 500
- RecoverPATCH /incident/{id} → 200
Everything you need to test integrations, not just endpoints.
Built for Dev, QA and DevOps teams who can't afford to wait for third-party systems to be available, stable or properly sandboxed.
Realistic API simulation
- REST APIs
- Control over responses
- Real-like behaviour
Scenario building
- Visual scenario builder
- AI-drafted scenarios
- Assertions & replay
Advanced scenario testing
- Error simulation
- Edge cases
- Failure scenarios
Dynamic response control
- Context-aware responses
- Dynamic logic
- Real-time control
Flexible environments
- Isolated setups
- Multiple workflows
- Parallel testing
Not just the happy path.
Most integration bugs hide in paths nobody could test: the callback that never arrives, the retry that fires twice, the renamed field. With neoSim you trigger them on purpose, as often as you need.
Normal
The expected path with realistic payloads and timing.
Failure
Errors, rejected requests, timeouts and silent services.
Async
Webhooks and callbacks that arrive late, fail or retry.
Edge case
Unexpected conditions and malformed data.
Load
High volume without vendor throttling. Available on Enterprise plans.
Version
Different API versions and configurations side by side.
Shooter detection alerts sent over Twilio SMS.
When a shooter is detected, the system sends an SMS alert through Twilio. Twilio accepts the request right away, but whether the message actually reaches a phone is only reported later. That failure case is the one that matters most, and the one a live service won't produce on request.
- Accepted request + Message SID
- Basic 4xx / 5xx errors
- Queued, sent and delivered callbacks
- Failed and undelivered callbacks
- Carrier errors: unreachable handset, block, spam filter
- Webhook retries
- Everything on the left, too
50+ simulators, ready on day one.
Each one reproduces real behaviour like expiring tokens, request limits and delivery callbacks, not just an endpoint list.
New simulators are added regularly. Tell us what you integrate with.
Request a simulator →From API mocking to system simulation.
neoSim Simulate goes beyond individual API responses to simulate how connected systems, integrations and real-world scenarios behave.
One simulator, three teams unblocked.
Build before access arrives
Start integration code on day one, without waiting for test accounts or licences.
Test the paths that break
Force timeouts, rate limits and bad payloads, then replay them on every release.
Keep pipelines green
Run CI in parallel against always-on environments, with no flaky sandboxes.
Less waiting on other systems. Fewer surprises in production.
What changes when third-party availability stops deciding when your team can test.
Faster integration delivery
Build and test before vendor access, test accounts or partner environments are ready, and release on your own schedule.
Lower production risk
Find integration problems, especially in failure handling, before customers do. Fewer escalations and outages follow.
Lower testing cost
Test runs don't use paid API quota or usage fees, and there's less dependency-driven test infrastructure to keep running.
More engineering output
Teams test independently and in parallel instead of queuing for one shared sandbox, with no extra headcount.
Across mass notification, video & VMS, geolocation, enterprise platforms such as identity, CRM and ITSM, and cybersecurity platforms. We've debugged these integration failure paths ourselves on real deployments. neoSim Simulate turns that experience into a simulation environment your team can run again and again.
neoSim Data
Building DLP, DSPM or classification engines? Generate synthetic sensitive data at scale and benchmark your scanner against ground truth.
What's the hardest integration for your team to test today?
Start there. Prove the value on one integration, then expand.
- 1Pick the integration that's hardest to test.
- 2Define three critical scenarios, including the failures you can't trigger today.
- 3Run a proof of value on the free plan, then decide.
Cloud-hosted by Neova. On-premise available on Enterprise.