Cursor vs Claude Code vs Codex for Mobile Development

Comparisons of AI coding tools tend to age badly. Benchmarks change monthly, pricing tiers shuffle, and every vendor ships a feature that closes last quarter's gap. What changes much more slowly is how each tool fits into the way you work: in an editor or a terminal, while you watch or in the background, one file at a time or across a whole migration.

This comparison of Cursor vs Claude Code vs Codex focuses on that, for people building mobile apps with React Native, Expo or native code. It covers what each tool is, how they compare for mobile-specific work, project instruction files, using two together, and a simple way to choose on your own codebase rather than someone else's benchmark.

Key takeaways

• Cursor is an AI-first code editor, strongest when you're in the code yourself: completions, inline edits and an agent beside your files.
• Claude Code is an agent built around the terminal, also available in IDEs, on desktop and on the web; strong at multi-file tasks it can verify by running commands.
• Codex is OpenAI's coding agent, available as a CLI, an IDE extension, cloud tasks and inside ChatGPT's apps.
• For mobile work, feedback loops matter most: type checks, tests, expo-doctor, builds and screenshots let any agent check its own work.
• Many developers combine an editor tool with a terminal agent. Trial them on three real tasks from your own repository before committing.

The short answer

What each tool is

Cursor is a code editor built on VS Code, so your extensions and keybindings mostly carry over. AI is woven through it: tab completions that predict your next edit, inline changes to a selection, and an agent that can edit many files and run terminal commands. Project instructions live in rules files under .cursor/rules, and Cursor also reads AGENTS.md.

Claude Code is Anthropic's agentic coding tool. It started in the terminal and now also runs in VS Code and JetBrains IDEs, a desktop app and the web. It reads your codebase, edits files, runs commands such as tests and builds, and reads project instructions from CLAUDE.md (or an existing AGENTS.md). Hooks can run checks automatically after edits, and MCP servers connect it to other tools.

Codex is OpenAI's coding agent. It's available as the Codex CLI, an IDE extension, Codex Cloud for tasks that run remotely, and inside ChatGPT's web, desktop and mobile apps, with GitHub integrations. It uses AGENTS.md for project instructions.

Side by side for mobile work

On paper the columns look similar, and they are converging. The practical differences are in ergonomics: where you spend your day, how much you watch the agent work, and how each tool's review flow suits your team.

Where mobile development is different

Mobile work has longer, more physical feedback loops than web work, and that shapes how well any assistant performs:

• Two platforms. Code that works on iOS can break on Android. An agent can't see that unless something tells it.
• Native builds. Gradle and CocoaPods failures produce long logs. Agents that can run the build and read the real error fix far more than agents guessing from a pasted fragment.
• Simulators and devices. None of these tools sees your simulator by default. MCP servers close the gap: Expo's MCP server, for example, lets assistants take screenshots of the running app and tap elements by testID (SDK 54 and later, with the expo-mcp package).
• Stores and signing. Credentials, certificates and store declarations should stay out of every assistant's reach, whichever you choose.

The common thread: give the tool commands it can run to check itself (npx tsc --noEmit, lint, npx jest, npx expo-doctor, a build) and its output gets much better.

One instructions file, not three

Each tool has its own project instructions file, but all three can now read AGENTS.md. If your team uses more than one tool, keep that single file as the source of truth for your commands, conventions and "never touch" list, rather than maintaining three diverging copies. Keep it short: commands to run, folder conventions, libraries to prefer, and what's off limits (native folders if you use prebuild, .env files, signing settings).

Using two together

A popular pattern is an editor tool for hands-on work plus a terminal agent for larger tasks. It works well with a few rules:

• Don't let two agents edit the same files at once. Give background tasks their own branch or git worktree.
• Keep tasks small and reviewable, whichever tool produced them.
• Run the same checks on every change, regardless of which tool wrote it.

From the field: I use both Claude Code and Cursor daily, for code review, refactors and tests, and every change is reviewed by me before it's merged. I've used Codex far less, so its column here is based on its documentation rather than daily use. Whatever the tool, the review and the release pipeline (EAS, Fastlane, GitHub Actions, phased rollouts) are what keep a mobile app shippable.

Cost, limits and privacy

All three sell individual and team plans with usage limits, and heavy agent use is where limits and costs show up. Check current pricing for the way you'd actually work, not just the entry tier. For client or company code, also check each vendor's data handling: whether code can be used for training, retention settings and options for business accounts.

How to choose: a one-week trial

Pick three real tasks from your own backlog:

1. A bug fix with a clear reproduction.
2. Tests for an untested module.
3. A small migration, such as replacing a deprecated API across the app.

Run each with the tools you're considering, with the same instructions file and checks. Compare time to a merged pull request, the number of review corrections, and how often you had to step in. A week of your own work tells you more than any public benchmark.

Setting up Cursor for a React Native project

Cursor's project rules live in .cursor/rules as .mdc files with a short header. A rule scoped to your app's screens might look like this:

---
description: "React Native and Expo conventions for this repository"
globs: app/**/*.tsx, components/**/*.tsx
alwaysApply: false
---

- Use Expo Router; screens live in app/
- Server state with TanStack Query; no fetch calls inside components
- Use expo-image for images and FlashList for long lists
- After changes, run `npx tsc --noEmit` and `npx jest`

Keep rules short and specific; a few lines that encode real conventions beat a long list of generic advice. If you also use Claude Code or Codex, put the shared parts in AGENTS.md, which all three read.

FAQ

Is Claude Code better than Cursor?

They suit different working styles. Cursor is strongest when you're writing code yourself in an editor, with completions and inline edits. Claude Code is strongest when you hand off multi-file tasks it can verify by running commands. Many developers use both, and a short trial on your own codebase is the best way to decide.

Can I use Cursor and Claude Code together?

Yes. A common setup uses Cursor for hands-on editing and Claude Code in the terminal or IDE for larger tasks such as migrations and test writing. Avoid having both edit the same files at the same time, and run the same checks on all changes.

What is Codex?

Codex is OpenAI's coding agent. It runs as a command-line tool, an IDE extension, cloud tasks and inside ChatGPT's web, desktop and mobile apps, and it reads project instructions from an AGENTS.md file.

Which AI coding tool is best for React Native?

Any of the three can work well. What matters more is setup: a short instructions file, commands the tool can run to check itself (type checks, tests, expo-doctor, builds), an MCP server such as Expo's for docs and screenshots, and human review of every change.

Next steps

If you want help introducing AI coding tools to a mobile team, with instructions, guardrails and review habits that keep quality up, I can help. Get in touch, or see my services.

Sources

• Cursor documentation, Cursor
• Rules, Cursor documentation
• Claude Code overview, Anthropic
• Codex documentation, OpenAI
• AGENTS.md, AGENTS.md
• Expo MCP Server, Expo documentation