1. You describe the fault
Tell Belay what is going wrong, in your own words. For example: checkout times out under load.
What Belay does
Four capabilities for working in code that already exists. Three work in our internal prototype today, on TypeScript and Python. One is planned.
The four capabilities
The prototype also draws the codebase as a 3D structure you can look around. The drawings on this site are illustrations in that spirit. They are not screenshots.
| Capability | What it does | What you get | Status |
|---|---|---|---|
| Root-cause tracing | Follows a fault across logs, code, tests and recent changes. | A ranked list of likely causes, with the evidence for each. | In the prototype |
| Codebase mapping | Explains unfamiliar modules, data flows and dependencies. | Architecture notes and onboarding guides linked to source files. | In the prototype |
| Design pressure-testing | Reviews a proposed design for failure modes and scaling limits. | Review notes listing risks and open questions. | In the prototype |
| Safe-change workflow | Checks blast radius, suggests tests and prepares rollback steps before a risky edit. | A change plan with tests and a rollback path, for your approval. | Planned |
How a trace works, step by step
Four steps, drawn on an invented codebase. Use the buttons or the arrow keys to move between them.
2. Belay reads the code
It follows the fault across logs, code, tests and recent changes. It reads. It does not edit.
3. It ranks the likely causes
You get a ranked list of likely causes, each with the files, tests and assumptions behind it, so you can check the reasoning.
4. You decide
You choose what happens next. Belay changes nothing until you say so.
The principles behind it
A belayer holds the rope and the climber makes every move. Belay is built on the same rule.
- Developer leadsBelay proposes, you decide. Nothing ships without a human say-so.
- Show the traceEvery answer cites the files, tests and assumptions behind it, so you can check the reasoning.
- Catch the fallBlast-radius checks, tests and rollbacks come before risky changes. The safe-change workflow that carries this principle is planned.
- Leave them strongerBelay explains the system as well as the fix, so the team keeps growing.
What Belay will not do
How your code will be handled- Belay is designed so that nothing is merged or deployed without a human decision.
- Each answer is meant to cite the files, tests and assumptions behind it. If you cannot check an answer, treat it as a guess.
- We make no claims about time saved. We will publish a time-to-diagnosis benchmark with our design partners first.
What works today, and what comes next
Checked 10 November 2026.
In our internal prototype
These work today, inside our team only. Nobody outside the team can use Belay yet.
- Root-cause tracing, for TypeScript and Python
- Codebase mapping
- Design pressure-testing
- A 3D view of the codebase
What's next
Targets, counted from the plan's first month, February 2027. They may move.
- Root-cause tracing with the first three design partnersQ2 2027
- A published time-to-diagnosis benchmark with partnersQ3 2027
- Team plans with repository integrationsQ4 2027
- A self-hosted option for enterprise pilotsQ1 2028
- IDE integrationsBy Q3 2028
- Private deployment, admin controls and compliance reportingFrom Q3 2028
- The safe-change workflowNo target yet
- An audit log of every stepNo target yet
- A data-handling policy, including no training on customer codeNo target yet
We are looking for design partners
5 to 8 engineering teams that work on large or legacy codebases.