Apex classes, SOQL, DML, triggers and Salesforce flows execute for real against an embedded database. A typical test finishes in tens of milliseconds instead of a four-minute round trip. When you are ready to ship, the same tool validates in your org and deploys exactly the bytes that passed.
curl -fsSL https://testnimbus.dev/install.sh | shFour open-source Apex suites, 837 tests, run once against a Salesforce org (deploy, then test) and once on Nimbus. Every test passes in both. Measured 2026-08-17.
Nimbus parses every class, interface, trigger and flow in the project and interprets it directly. There is no transpilation step and nothing is stubbed.
Nimbus executes Apex and flows against a real embedded PostgreSQL. Queries return rows, triggers fire, record-triggered flows run and DML persists inside the test transaction. There is no simulated runtime and no stubbed return value, and a typical test still completes in tens of milliseconds.
Why an embedded databaseNimbus reads the flow metadata in your repo and runs it. Record-triggered flows fire on DML in the platform's order of execution, autolaunched flows and subflows run with their decisions and formulas, and platform event flows subscribe locally. Nothing is deployed and the test class needs no changes.
How flow execution worksThe Apex Replay Debugger works from a log after the fact. Nimbus attaches to the running test, so you get breakpoints, stepping and variable inspection while it executes.
See the debuggerNimbus changes your code in small ways, flipping operators, negating conditions and altering return values, then reruns the tests to see whether they notice. 75% line coverage says nothing about whether a test would fail when the code is wrong.
How mutation testing worksEach run produces an OpenTelemetry trace of method calls, SOQL, DML, triggers, branches and assignments, shown as a tree you can expand. It replaces reading a 40,000-line debug log.
Explore traces and analyticsnimbus compare runs the same tests in a connected org and diffs the outcomes, governor usage and traces against the local run. Fidelity is something you check on your own code rather than something we claim.
The org parity recordEach entry links to its own page, with the details and the limitations.
Nimbus covers the tests that exercise business logic, queries and automation. These do not run locally.
Every developer gets Pro free during the beta.
For individual developers
nimbus deploy)nimbus sf)Free during the beta, no card required
nimbus daemon)nimbus serve): REST and Pub/Sub gRPCNimbus runs the tests that exercise business logic, SOQL, triggers, flows and class behaviour. Sharing rules, UI and approvals still need an org. Every gap is listed on the comparison page.
No. A typical test completes in tens of milliseconds, real SOQL and DML included. The embedded PostgreSQL is tuned for test workloads, with a unix socket and fsync and WAL switched off. In head-to-head runs Nimbus finishes whole open-source suites that in-memory Apex simulators time out on.
Everything Nimbus supports runs on the developer machine. No source code or schema leaves the laptop. The org remains the deployment target and the system of record.
Pre-merge: nimbus test in CI with no connected org. JUnit XML and Cobertura go to the tools you already run. Pre-deploy: nimbus release validate runs the local gates plus a real Salesforce check-only validation and writes a receipt. After approval, nimbus release deploy ships exactly that payload.
Nimbus is a single binary for macOS, Linux and Windows. The Free tier needs no account and no card. During the beta, sign up for a free Pro license.
Questions go to the Slack or to support@testnimbus.dev.
curl -fsSL https://testnimbus.dev/install.sh | sh