--- title: "Claude, Codex and Gemini: Which AI Coding Assistant for Which Job" url: https://phatdev.net/en/blog/claude-codex-gemini-for-coding lang: en updated: 2026-10-21 alternate: vi: https://phatdev.net/vi/blog/claude-codex-gemini-for-coding markdown: https://phatdev.net/en/blog/claude-codex-gemini-for-coding.md --- # Claude, Codex and Gemini: Which AI Coding Assistant for Which Job > Three AI coding assistants differ in how you use them, how you pay and what happens to your data. A plain-words comparison from official docs checked on 21 October 2026, including Gemini CLI moving to Antigravity CLI. Categories: AI | Published: 2026-10-21 | Level: Beginner | 6 min read Tags: claude, codex, gemini, ai-coding, claude-code, comparison It is Saturday and you have one job: fix the cart on your shop's website. You open three tabs, Claude, ChatGPT and Gemini, and paste the same error into all of them. You get three different answers. You do not know which to trust, or which one deserves your money. I build websites and software to order, and I use all three in my own work. This post does not rank them. It shows where they differ so you can match the tool to the job. Everything about plans, prices and features below was checked on the official pages on 21 October 2026. These things change fast, so open the source pages (linked at the end) before you buy anything. ## The three names, and what they are Claude is Anthropic's family of AI models. The current ones are Claude Opus 5.5, Sonnet 5.5 and Haiku 5.5 (Opus for hard work, Haiku the fastest and cheapest). Their coding tool is called Claude Code. Codex is OpenAI's coding tool and agent. It comes as a terminal version (Codex CLI), an editor extension, a desktop app and a web version. Gemini is Google's model family. For coding you usually meet two things: the Gemini API, which developers call from their own programs, and a command-line tool. That tool had a big change that many people have missed, covered below. ## How you use them There are three ways. The first is chat: you paste some code into a chat box, the AI answers, you copy the result back. It is easy, but the AI cannot see your whole project. The second is the terminal, the window where you type commands. Here the AI can read your project folder, edit files, run checks and report back. The third is inside your code editor, where changes appear as a before-and-after comparison. ![Three ways to use a coding assistant: a chat box, a terminal and an editor, all connected to one assistant](https://phatdev.net/uploads/blog/claude-codex-gemini-for-coding/surfaces-1920.webp) According to the official docs, Claude Code runs in the terminal, in VS Code (and Cursor), in JetBrains, as a desktop app and on the web. Codex has the CLI, an extension for VS Code, Cursor and Windsurf, a desktop app and Codex Web. On Google's side, the command-line tool today is Antigravity CLI (the `agy` command). ## The Gemini CLI change you should know about On 19 May 2026 Google announced it was moving Gemini CLI to Antigravity CLI. From 18 June 2026, Gemini CLI stopped serving people on Google AI Pro, Google AI Ultra and the free individual tier. Gemini CLI remains available to enterprise customers (Gemini Code Assist Standard or Enterprise licences) and through paid API keys. Google also says plainly that Antigravity CLI does not match every feature of the old tool at launch. If you read an older tutorial saying you can sign in with a Google account and use Gemini CLI for free, check its publication date. ## What each one emphasises This section only repeats what each company says in its own documentation. It is not a quality ranking. I am not quoting benchmark scores either, because I have no reliable source to cite. The Claude Code docs stress learning your project: a notes file (CLAUDE.md) it reads at the start of each session, a planning mode before edits, rewind through checkpoints, helper agents (subagents) and hooks that run automatically around its actions. The Codex docs stress running in many places (your machine, your editor, the cloud) and two clear safety dials: the sandbox mode and the approval policy. The Codex CLI source is open under Apache-2.0. For Google, the Antigravity CLI docs say it runs several agents asynchronously in the background and shares its engine with the Antigravity desktop app. The Gemini API has a free tier, which is handy for learning to call a model. ## How you pay The mechanism matters more than the numbers, because numbers keep changing. There are two routes: a subscription plan, or pay-per-use through the API. | | Subscription | Pay by API | |---|---|---| | Claude Code | Included in every paid plan (Pro, Max, Team, Enterprise). Usage limits are shared with the Claude apps, with a five-hour window plus weekly limits | Per million tokens, price depends on the model | | Codex | Included in ChatGPT plans, including Free and Go. Shares limits with ChatGPT, with five-hour windows and possible weekly limits. Extra use is bought as credits | Standard API rates, not tied to plan limits | | Gemini | Antigravity CLI signs in with Free, Pro or Ultra Google plans, or with an API key | Gemini API: per million tokens, with a limited free tier | A few sourced numbers, as of 21 October 2026: Claude Pro is 20 USD a month when billed monthly, Max starts at 100 USD. On the API, Opus 5.5 costs 4 USD per million input tokens and 20 USD per million output tokens, Sonnet 5.5 is 2 and 10 USD, Haiku 5.5 is 0.10 and 0.50 USD. ChatGPT Plus is 20 USD a month and Pro starts at 100 USD. Gemini API prices vary by model and some change on fixed dates in 2026 and 2027, so I am not copying them here. Check the pricing page. The thing to remember: a plan has limits per time window, while an API has no cap until your money runs out. Heavy daily use will hit a limit on any of them at some point, and [Common Problems When Using AI to Write Code, and How to Avoid Them](https://phatdev.net/en/blog/ai-coding-common-problems) covers what to do then. ## Where your code goes Many people skip this. All three vendors separate personal accounts from business accounts. For Claude, Free, Pro and Max accounts let you choose whether your data may be used to improve models. For Team, Enterprise and API use, Anthropic states it does not train on code or prompts sent through Claude Code unless you join a separate programme on purpose. For OpenAI, the help centre says business and API data is not used to improve models by default. For Plus and Pro, conversations may be used unless you switch that off in ChatGPT's data controls. For Google, the Gemini API pricing page says the free tier may use your content to improve products, while the paid tier does not for most models. A simple rule: do not paste a client's code into a free personal account. Use a business plan or the API, and read the terms first. ## How I split work across the three I do not look for a winner. I split work by type. Long jobs that touch many files and need repeated test runs go to a terminal tool that can run its own checks. Quick questions and reading unfamiliar code are fine in chat. Anything that calls a model from inside a product goes through an API. ![Sorting jobs by type to different tools](https://phatdev.net/uploads/blog/claude-codex-gemini-for-coding/roles-1920.webp) The habit that has helped most is letting one AI review another AI's work. An AI that just wrote code is poor at spotting its own mistakes. Give the change (the diff) and the original request to a different tool and ask where it drifts from the request or might break. You still make the final call. Two AIs agreeing does not make something correct, so run the tests anyway. ![One AI writes, another reads it back, a person decides](https://phatdev.net/uploads/blog/claude-codex-gemini-for-coding/crosscheck-1920.webp) If you want several AIs on one big job, read [Handing a Big Job to Several AIs Without Breaking Things](https://phatdev.net/en/blog/agentic-workflow-orchestrator). For writing requests clearly, see [How to Ask an AI So It Gets It Right and Stops Making Things Up](https://phatdev.net/en/blog/prompt-engineering-for-developers). ## Which one to pick If you are just starting and only ask questions about code, a chat box is enough and you do not need to pay for more. If you write code every day, try one tool's trial or cheapest plan for two weeks on your real project before thinking about a second. Choose by how it feels to work with and by data terms that suit your clients, not by a score table you found online. If you are unsure which tool your team should use, I am happy to give an opinion based on your situation through the contact page. ## References - [Claude Code - Overview](https://code.claude.com/docs/en/overview) - [Claude - Pricing (kiểm 21/10/2026)](https://claude.com/pricing) - [Claude Code - Data usage](https://code.claude.com/docs/en/data-usage) - [OpenAI Codex CLI (GitHub)](https://github.com/openai/codex) - [Codex - Pricing (kiểm 21/10/2026)](https://learn.chatgpt.com/docs/pricing) - [OpenAI Help - Codex data controls](https://help.openai.com/en/articles/11369540) - [Google - Transitioning Gemini CLI to Antigravity CLI (19/05/2026)](https://developers.googleblog.com/en/an-important-update-transitioning-gemini-cli-to-antigravity-cli/) - [Antigravity CLI - Getting started](https://antigravity.google/docs/getting-started) - [Gemini API - Pricing (cập nhật 19/10/2026)](https://ai.google.dev/gemini-api/docs/pricing) ## Related posts - [Common Problems When Using AI to Write Code, and How to Avoid Them](https://phatdev.net/en/blog/ai-coding-common-problems.md) - [Handing a Big Job to Several AIs Without Breaking Things](https://phatdev.net/en/blog/agentic-workflow-orchestrator.md) - [How to Ask an AI So It Gets It Right and Stops Making Things Up](https://phatdev.net/en/blog/prompt-engineering-for-developers.md)