How to Set Up Devin 3 and Run Your First Task

Devin 3 is an autonomous AI software engineer from Cognition that plans, codes, and tests on its own cloud workspace. You give it a task in plain English, watch it work in a live browser view, and pull the changes back to your repo.

What is Devin 3?

Devin is not an autocomplete tool. It has its own shell, editor, and browser inside a sandboxed VM. The third version tightened its planning step and added better support for working alongside human reviewers.

It handles full tasks: “migrate this service from Flask to FastAPI”, “add pagination to the API and update the docs”. You supervise rather than type alongside it.

Is Devin 3 free?

No. Devin uses a paid subscription starting in the hundreds of dollars per month per seat, billed with an ACU (Agent Compute Unit) usage model. It is priced for companies, not hobbyists.

How do you connect a repository?

1. Create an account and set up a team workspace.
2. Install the Devin GitHub integration and grant access to the target repos.
3. Open a new session and pick the repository and branch.
4. Give Devin any setup commands it asks for (install, test, lint).

The setup commands are the make-or-break step. If npm install fails in the sandbox, Devin cannot work. Run them once locally and paste the exact strings.

How do you write a task Devin 3 can finish?

Scope it like a ticket, not a wish. “Add a POST /users endpoint that validates email, returns 201, and includes tests in tests/test_users.py” gives Devin a finish line.

It will produce a plan first. Read the plan — that is where you catch a misunderstanding before it burns an hour of compute.

What should you expect from the output?

Devin opens a PR with a summary, the diff, and often a short screen recording or test log. Small tasks land in 20-40 minutes; larger refactors take hours. Review the diff as carefully as any contractor’s. It is capable but not infallible, and it will occasionally fix a symptom rather than the cause.

Quick Summary

• Devin 3 is an autonomous coding agent with its own sandboxed VM.
• It is paid, billed per seat with ACU usage — not a free tool.
• Repository setup commands must work in the sandbox.
• Write ticket-style tasks with a clear finish line.
• Review the plan before the code, and the diff after.