Cursor vs Devin

ACU Cost Analysis for Devin

An ACU (Anthropic Compute Unit) represents roughly 15 minutes of continuous AI work. At $2.25 per ACU:

• Small bug fix (30 min) = 2 ACUs = $4.50
• Feature implementation (2 hours) = 8 ACUs = $18
• Large refactor (overnight, 8 hours) = 32 ACUs = $72
• Complex migration (40 hours) = 160 ACUs = $360

For individual developers or teams with light usage, Cursor's flat $20/month is often cheaper. For teams running large overnight jobs regularly, Devin's Teams plan at $500/month (250 ACUs included) can be more economical than multiple Cursor licenses.

Cursor: Interactive AI-Assisted Development

Cursor is fundamentally an enhanced IDE. It embeds Claude (the AI model) directly into VS Code as a native environment. Every keystroke, every selection, every context window is available. Cursor predicts entire functions via its Tab feature and offers intelligent code suggestions in real time. The developer stays in complete control—they see the prediction, approve or reject it, edit it, and drive the narrative forward.

This is a collaborative model. The AI augments human decision-making. You remain the architect; the AI is the pair programmer. For debugging, Cursor can read error messages and suggest fixes, but you decide whether to apply them. For exploring a new codebase, Cursor reads the files and explains the structure, but you navigate. For writing tests, Cursor drafts them, but you verify coverage.

This approach excels at: daily coding workflows, exploration, refactoring existing code, learning new frameworks, debugging complex issues, code reviews, and interactive problem-solving where context shifts rapidly.

Devin: Fully Autonomous Task Execution

Devin is an agent, not an editor. You describe a task (often via a GitHub issue: "implement feature X" or "fix bug Y") and Devin executes it end-to-end. It reads the codebase, plans the changes, writes code, runs tests, handles errors, and pushes commits—all without waiting for approval at each step. You can monitor progress on a dashboard, pause if needed, or take control, but the default posture is hands-off.

Devin has access to a terminal, GitHub, and your entire repository. It works sequentially through tasks with full autonomy. This is suitable for: overnight batch work, large standardized migrations, refactoring patterns applied across many files, implementing well-defined features from specifications, or handling routine maintenance tasks that would tie up a developer for hours.

The key difference: Cursor asks "What would you like me to code?" and you stay at the keyboard. Devin receives "Implement X" and you check back in when it's done (or after a set time).

Use Case Breakdown

Best for Cursor: Building a new feature from scratch where requirements evolve mid-development. Writing performance-critical algorithms where you want to explore trade-offs. Debugging a production issue where you need to experiment and pivot quickly. Learning a new library where you need interactive feedback. Code reviews where you need to understand design intent. Pair programming with the AI on complex logic.

Best for Devin: Migrating from one library to another across 50 files. Refactoring a specific pattern everywhere in the codebase. Implementing a well-defined feature from a detailed spec while you handle other work. Running overnight test suites and fixing failures without manual intervention. Standardized code generation (e.g., CRUD endpoints for multiple models). Large-scale documentation generation. Bulk updates to dependencies or configurations.

Both together: Most mature development teams use both. A developer uses Cursor for interactive work during business hours. If a large refactor or migration is identified, they draft a detailed GitHub issue, hand it to Devin with specific requirements, and let it run overnight. The next morning, they review Devin's work in Cursor, make adjustments, and merge.

Cost-Per-Task Economics

A developer working in Cursor on a 4-hour feature costs the company their hourly rate (say $50–$150/hr depending on seniority and location). Cursor's $20/month is an almost invisible overhead on that.

A Devin task that takes 4 hours (16 ACUs) costs $36 in ACU fees plus $1.67/month (1/300th of $500 Teams subscription). Compare that to paying a developer $200–$600 for the same 4 hours. The math strongly favors Devin for large, repetitive, or well-scoped work.

However, for exploratory work, novel problem-solving, and tasks where requirements are unclear, Cursor's flat fee and real-time collaboration model is more efficient and cost-effective.

Team Workflows & Complement

In well-run engineering teams:

• Daily development: Every engineer has Cursor. It's their coding partner for the day's work.
• Planned large tasks: Team leads identify migration, refactor, or bulk-update work and create GitHub issues. Devin is assigned those issues; it runs end-to-end.
• Review & iterate: Engineers review Devin's output in Cursor, tweak as needed, merge when ready.
• Overnight jobs: Long-running tasks (test fixes, dependency updates, documentation) run on Devin while the team sleeps.

This hybrid model maximizes both tools. Cursor handles the interactive, creative, problem-solving portions. Devin handles the repetitive, well-defined, scale-intensive portions.

Developer Control & Supervision

Cursor keeps the developer in the loop always. You see predictions before they're applied. You can reject, edit, or accept. The feedback loop is tight and interactive.

Devin operates with optional supervision. You can enable "human-in-the-loop" mode to approve major decisions, or let it run fully autonomous. For critical systems or unfamiliar codebases, many teams choose the approval mode. For routine tasks or well-tested patterns, fully autonomous is faster.

Integration Depth

Cursor is your IDE. It integrates with your editor, your extensions, your workflow, your VS Code settings. It's a drop-in replacement. This depth means it understands your code faster and adapts to your style.

Devin integrates via GitHub and APIs. It's broader but shallower—it works with any repo, any language, any setup, but it doesn't know your editor preferences or personal coding style.