Comparison
Relay vs Greptile
Greptile reviews pull requests with an AI agent that understands your codebase. Relay proves the changed lines actually ran under test. They answer different questions — many teams would sensibly run both.
Facts checked against official docs on 2026-08-18
What Greptile is
Greptile is "an AI code review agent that automatically reviews every pull request with complete understanding of your codebase." It builds a graph of the repository and posts findings as PR comments with suggested fixes in minutes. Its TREX agent additionally runs the PR branch in a sandbox — services, dev servers, browser agents, targeted tests — and attaches runtime evidence (logs, screenshots, traces) to the PR.
Pricing: Starter free (1 developer, 50 credits/mo) · Pro $30/seat/mo (50 credits/seat, $1 per extra; a TREX review is 3 credits) · Enterprise custom. As of August 2026.
Side by side
| Greptile | Relay | |
|---|---|---|
| LLM review of the diff | Yes — parallel agents with a codebase graph | No — Relay does not read your code and judge it |
| Runs your tests | TREX runs the PR branch and targeted tests in a cloud sandbox | Yes — your suite, locally, through your own runner |
| Measures coverage of the changed lines | Not documented | Yes — the diff intersected with a real run’s coverage report |
| Signed, deterministic verdict artifact | Not documented | Yes — Ed25519-signed receipts, snapshot-bound to the exact diff |
| PR comments and suggested fixes | Yes | No |
| Runs locally, before the PR exists | No — reviews PRs | Yes — `relayevals try` needs no PR, no account, and writes nothing |
The honest take
If you want a reviewer that reads every PR with context and catches issues a human would miss, Greptile is built for exactly that, and TREX’s runtime exploration goes beyond what Relay does — Relay never spins up browsers or explores your app. What Greptile’s public docs do not claim is the thing Relay is for: a per-line measurement that the changed lines executed, signed and bound to the diff, decided without a model in the loop. An opinion about your diff and evidence about your diff are different instruments.
Sources
- https://www.greptile.com/
- https://www.greptile.com/docs/introduction
- https://www.greptile.com/trex
- https://www.greptile.com/pricing
See what Relay measures on your own repository — one command, no setup, writes nothing: relayevals try. Docs · The full guide to verifying AI-generated code