# AI code review that runs your code.

Test Run EXecute

**TREX** runs your PR branch in a sandbox to find the bugs that only show up at runtime. It starts services, mocks inputs, clicks through UI flows, and leaves the logs, screenshots, and traces on the PR.

[contact sales](/contact?source=trex)

[get started](https://app.greptile.com/signup)

no credit card required • 14-day free trial

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## How TREX validates a PR

### How it works

#### 01

##### Understands the change

TREX looks at the PR, your repo, your test suite, and your stack to figure out what needs to run.

#### 02

##### Runs it in a sandbox

TREX spins up the tools it needs: services, dev servers, mocks, API calls, browser agents, or targeted tests.

#### 03

##### Shows what broke

When something fails, TREX traces it back to the relevant code and leaves a PR comment along with the evidence.

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## Get bug reports with screenshots and logs

Greptile with TREX catches ~20% more bugs than review alone, the ones that only surface when the code actually runs.

[Sign up](https://app.greptile.com/signup)

### Evidence on every finding

TREX does not just say something failed. It shows what happened with logs, screenshots, traces, scripts, videos, or API output attached to the PR comment.

#### Works with your stack

TREX runs against the dependencies, frameworks, and test setup your repo already uses.

#### Tests end to end

TREX mocks inputs, spins up dev servers, and uses browser agents to click through your UI.

\[ MORE FEATURES \]

## Explore other features at Greptile

Find out more about how teams are using Greptile

[See docs](https://www.greptile.com/docs/introduction)

### [Agent](/agent.md)

The code reviewer that catches real bugs

[Learn more](/agent.md)

### [Independence](/independence.md)

The independent code validator

[Learn more](/independence.md)

### [Learning & Custom Context](/learning.md)

Code reviews that get personalized over time

[Learn more](/learning.md)

## Let Greptile run the PR before it merges.

[View Pricing](/pricing.md)

[Start now](https://app.greptile.com/signup)