Google Antigravity, OpenAI Codex CLI, and Anthropic Claude Code represent three fundamentally different bets on how AI-native software development should work. Each tool comes from a company with its own foundational model, its own developer ecosystem, and its own philosophy about the boundary between human intent and machine execution. If you write code for a living, the choice between them shapes your daily workflow, your costs, and the ceiling on what you can delegate to an agent.
This comparison exists because the surface-level pitch for all three sounds identical: give the AI a task, watch it write and run code. The implementation details diverge sharply. Antigravity is a full IDE replacement. Codex CLI is an open-source terminal tool backed by cloud sandboxes. Claude Code is a terminal-first agent with extensions into editors and the browser. Understanding where each one excels—and where it falls short—requires looking past marketing copy at architecture, benchmark scores, pricing math, and real autonomy boundaries.
This article covers hard numbers: SWE-bench Verified scores, context window sizes, per-token costs, and ecosystem lock-in. No personal testing claims, no anecdotes. Just the publicly available data that matters when you are deciding which agent to wire into your development stack.
Architecture and Paradigm
The first divergence is structural. Each tool occupies a different surface in the developer toolchain.
Google Antigravity: The IDE Replacement
Antigravity launched on November 18, 2025 as a VS Code fork rebuilt around Gemini. With the Antigravity 2.0 announcement at Google I/O 2026 (May 19, 2026), it expanded into a multi-surface platform: desktop IDE, a Go-based CLI, a public SDK for hosting custom agents, and a Managed Agents API tier. It is the only tool in this comparison that replaces your editor entirely. The IDE includes a built-in Chromium browser for catching UI regressions, support for dynamic sub-agents, and scheduled background tasks. It is Gemini-native by default, though it also supports third-party models including Claude and GPT via proxy.
OpenAI Codex CLI: The Open-Source Terminal Agent
Codex CLI is a Rust-built, open-source (Apache 2.0) terminal tool. You install it, point it at a directory, and it reads, modifies, and runs code on your machine. The cloud counterpart—the Codex app inside ChatGPT—spins up a sandboxed clone of your repository, executes the task asynchronously, and notifies you when the pull request is ready. Codex CLI does not ship an editor. It does not bundle a browser. It is the thinnest wrapper in this comparison: a terminal binary that calls OpenAI models and writes to your filesystem.
Anthropic Claude Code: Terminal-First, Multi-Surface
Claude Code started as a terminal CLI and has since expanded to seven surfaces: macOS/Linux/Windows CLI, VS Code extension, JetBrains plugin, a desktop app, a web interface at claude.ai/code, iOS, and a Chrome extension (beta) for debugging live web apps. It remains terminal-first in philosophy—flags, pipes, and scripting are first-class citizens—but the multi-surface availability means it can meet developers wherever they already work. Unlike Antigravity, it does not replace your editor. Unlike Codex CLI, it is not open-source.
Models Under the Hood
Each tool is tightly coupled to its parent company's model family, though the degree of coupling varies.
| Tool | Primary Models | Third-Party Model Support |
|---|---|---|
| Antigravity 2.0 | Gemini 3.5 Flash (default), Gemini 3.1 Pro | Yes—Claude Sonnet/Opus 4.6, GPT models via proxy |
| Codex CLI | GPT-5.3-Codex (codex-1 lineage), o3, o4-mini | Limited—primarily OpenAI ecosystem |
| Claude Code | Opus 4.7 (default), Sonnet 4.6, Sonnet 4.5 | No—Anthropic models only |
Antigravity is the most model-flexible of the three: you can swap in non-Gemini models through community proxies. Claude Code is the most locked-in, running exclusively on Anthropic’s model family. Codex CLI sits in between—it is open-source, so forks exist that support other providers, but the official tool targets OpenAI models.
Context Windows
Context window size determines how much of your codebase an agent can hold in memory during a single session before it starts compacting or forgetting earlier context.
| Tool | Context Window | Practical Notes |
|---|---|---|
| Antigravity 2.0 | 1M tokens (Gemini 3.5 Flash) | ~30,000 lines of code or ~1,500 pages of text in a single session |
| Codex CLI | ~258K usable (400K model capacity minus 128K reserved, times 0.95 compaction threshold) | GPT-5.5 API supports 1M, but Codex CLI caps at 400K; community requests to raise this are open |
| Claude Code | 200K (standard) / 1M (Opus 4.7, Sonnet 4.6) | Reading four large files plus a build log can consume 50K+ tokens before you ask a question; compaction kicks in after ~3–4 deep iterations on 200K |
Antigravity holds a clear advantage in raw context capacity at the default tier. Claude Code’s newer models (Opus 4.7, Sonnet 4.6) match that 1M figure, but only on Enterprise or Max plans. Codex CLI’s effective window is the smallest of the three, though OpenAI is working on expanding it.
Autonomy Levels
All three tools offer a spectrum from supervised to fully autonomous operation. The defaults and guardrails differ significantly.
Antigravity introduced an agentic mode that lets the AI plan multi-step changes, execute them, run tests, and iterate without human checkpoints. The Deep Think reasoning mode adds extended deliberation for complex tasks like data migrations and schema refactors. With Antigravity 2.0, multi-agent orchestration lets you spin up parallel sub-agents that work on different parts of a project simultaneously.
Codex CLI offers a full-auto mode where you queue a task, the cloud sandbox clones your repo, the agent executes autonomously, and you get a notification when the PR is ready for review. This is the closest any of the three comes to a fire-and-forget workflow. The local CLI also supports suggest mode (proposes changes without applying them) and auto-apply mode.
Claude Code provides an auto-accept mode that bypasses confirmation prompts, letting the agent chain tool calls without human intervention. It also supports headless operation via CLI flags for CI/CD integration. The default mode requires human approval for file writes and command execution, which is more conservative than Codex’s full-auto default in the cloud app.
Benchmark Performance
SWE-bench Verified is the most widely cited benchmark for coding agents. It tests an agent’s ability to resolve real GitHub issues across multiple languages and repositories.
| Tool / Model | SWE-bench Verified | SWE-bench Pro | Terminal-Bench 2.0 |
|---|---|---|---|
| Claude Code (Opus 4.7) | 87.6% | — | — |
| Codex (GPT-5.3-Codex) | 85.0% | 56.8% | 77.3% |
| Antigravity (Gemini 3.5 Flash) | 76.2% | — | — |
Claude Code leads on SWE-bench Verified, the gold-standard coding benchmark. Codex CLI holds the top Terminal-Bench score at 77.3%, reflecting its strength in terminal-native workflows. Antigravity trails on SWE-bench Verified but compensates with speed: Gemini 3.5 Flash is optimized for 12x faster agent execution, meaning it completes more tasks per unit time even if per-task accuracy is lower.
Benchmark scores should be interpreted carefully. SWE-bench Verified tests bug-fixing on established open-source repos—it does not measure greenfield development, UI work, or multi-service orchestration where Antigravity’s parallel agents may have an edge.
Pricing Breakdown
All three tools offer free or low-cost entry points, but costs diverge sharply at professional scale.
| Tier | Antigravity | Codex CLI | Claude Code |
|---|---|---|---|
| Free | $0 — 20 agent requests/day | $0 — CLI is open-source (Apache 2.0); bring your own API key | $0 — limited via free claude.ai tier |
| Standard / Plus | $20/mo (AI Pro) | $20/mo (ChatGPT Plus) — Codex access included | $20/mo (Pro) — Claude Code included |
| Professional | $100/mo (AI Ultra Developer) or $200/mo (AI Ultra) | $100/mo (ChatGPT Pro, currently 10x usage) | $100/mo (Team Premium, 5-seat minimum) or $200/mo (Max) |
| API / Pay-as-you-go | Gemini 3.5 Flash: competitive per-token pricing | GPT-5.3-Codex: ~$2/$8 per MTok (input/output) | Opus 4.7: $5/$25 per MTok (input/output) |
| Enterprise | Custom pricing via Google Cloud | Custom pricing via OpenAI | Custom pricing via Anthropic |
On API pricing, Codex is the most cost-efficient per token. OpenAI claims Codex CLI is approximately 4x more token-efficient than Claude Code for equivalent tasks, which compounds the per-token savings. Antigravity’s credit system ($0.01 per credit, bulk packs at $199 for 20,000 credits) adds a layer of cost indirection that makes direct comparison harder.
For Claude Code specifically, Anthropic publishes anchor numbers: approximately $13 per developer per active day on average, with 90% of users below $30/day, translating to $150–$250 per developer per month at scale before optimization.
Ecosystem and Lock-In
Your choice of coding agent is also a bet on an ecosystem.
Antigravity integrates with Google Cloud, Firebase, Cloud Run, and the broader Google developer toolchain. If your infrastructure runs on GCP, Antigravity’s deployment and monitoring integrations are the tightest of the three. The public SDK and Managed Agents API mean you can host custom agents on third-party infrastructure, partially mitigating lock-in.
Codex CLI ties into the OpenAI API ecosystem. Its open-source nature (Apache 2.0) is the strongest hedge against lock-in—you can fork the CLI and point it at any OpenAI-compatible API. The Codex cloud app, however, is proprietary and requires a ChatGPT subscription.
Claude Code connects to the Anthropic API. It integrates with VS Code, JetBrains, and GitHub (for PR workflows), but the underlying model calls are Anthropic-only. There is no open-source component. If Anthropic changes pricing or deprecates a model, there is no self-hosted fallback.
Open-Source Status
| Tool | Open Source? | License |
|---|---|---|
| Antigravity | No (IDE is proprietary; SDK is public) | Proprietary |
| Codex CLI | Yes | Apache 2.0 |
| Claude Code | No | Proprietary |
Master Comparison Table
| Category | Antigravity 2.0 | Codex CLI | Claude Code |
|---|---|---|---|
| Paradigm | IDE replacement (VS Code fork) | Terminal CLI + cloud sandbox | Terminal CLI + editor extensions |
| Primary Model | Gemini 3.5 Flash | GPT-5.3-Codex | Claude Opus 4.7 |
| Context Window | 1M tokens | ~258K usable (400K model) | 200K–1M (plan-dependent) |
| SWE-bench Verified | 76.2% | 85.0% | 87.6% |
| Terminal-Bench | — | 77.3% | — |
| Free Tier | 20 agent requests/day | Open-source CLI (BYO API key) | Limited free tier |
| Pro Price | $20/mo | $20/mo (ChatGPT Plus) | $20/mo |
| Power Price | $100–$200/mo | $100/mo (Pro) | $100–$200/mo |
| Open Source | No (SDK is public) | Yes (Apache 2.0) | No |
| Multi-Model | Yes (Gemini + third-party) | Limited (OpenAI models) | No (Anthropic only) |
| Multi-Agent | Yes (parallel sub-agents) | Yes (desktop multi-project) | Limited (sequential) |
| Autonomy | Agentic mode + Deep Think | Full-auto cloud sandbox | Auto-accept + headless mode |
| Ecosystem | Google Cloud / Firebase | OpenAI API | Anthropic API |
| Platforms | Desktop IDE, CLI, SDK | Terminal (macOS/Linux/Windows) | CLI, VS Code, JetBrains, Desktop, Web, iOS, Chrome |
When Each Tool Falls Short
When Antigravity Is the Wrong Choice
You need maximum coding accuracy. At 76.2% on SWE-bench Verified, Antigravity trails both competitors by a significant margin. For mission-critical bug fixes where first-attempt accuracy matters, the 11-point gap to Claude Code is substantial.
You prefer your existing editor. Antigravity is a full IDE replacement. If your muscle memory, keybindings, and extension ecosystem are built around VS Code or a JetBrains IDE, switching editors is a high-friction commitment that the other two tools do not require.
You need open-source transparency. The IDE is proprietary. You cannot audit the agent’s code, self-host it, or fork it. The SDK is public, but the core product is closed.
When Codex CLI Is the Wrong Choice
You work with massive codebases. The ~258K effective context window is the smallest of the three. On a large monorepo, compaction kicks in sooner, and the agent loses track of cross-file dependencies faster than Antigravity or Claude Code with 1M context.
You want an integrated development environment. Codex CLI is a terminal tool. There is no built-in file browser, no integrated debugger, no visual diff viewer. You need to pair it with your own editor and terminal setup.
You want multi-model flexibility. While the CLI is open-source and forkable, the official tool only supports OpenAI models. Community forks exist for other providers, but they are unofficial and may lag behind updates.
When Claude Code Is the Wrong Choice
You are optimizing for cost. At $5/$25 per MTok for Opus 4.7 and an average of $13 per developer per active day, Claude Code is the most expensive option at scale. Codex CLI’s claim of 4x greater token efficiency makes the gap even wider in practice.
You want open-source guarantees. Claude Code is entirely proprietary. No source code, no self-hosting, no forking. If Anthropic changes terms, raises prices, or deprecates a model version, your options are to accept or migrate.
You need parallel multi-agent workflows. Claude Code executes tasks sequentially. Antigravity 2.0’s parallel sub-agents and Codex’s multi-project desktop command center both handle concurrent workstreams more natively.
The Bottom Line: Recommendation Matrix
| Your Priority | Best Choice | Why |
|---|---|---|
| Maximum coding accuracy | Claude Code | 87.6% SWE-bench Verified, highest published score |
| Lowest cost at scale | Codex CLI | Open-source CLI + 4x token efficiency claim + competitive API pricing |
| Largest context window | Antigravity | 1M tokens at default tier; no plan upgrade needed |
| Open-source transparency | Codex CLI | Apache 2.0 license, full source on GitHub |
| Greenfield prototyping speed | Antigravity | Parallel sub-agents + built-in browser + free tier removes cost friction |
| Terminal-native workflows | Codex CLI | 77.3% Terminal-Bench score, designed for CLI-first developers |
| Editor flexibility | Claude Code | VS Code, JetBrains, Desktop, Web, iOS, Chrome—seven surfaces |
| Google Cloud infrastructure | Antigravity | Native GCP, Firebase, Cloud Run integration |
| Fire-and-forget autonomy | Codex CLI | Cloud sandbox clones repo, works async, delivers PR |
| Creative / vibe coding | Claude Code | Strongest first-attempt understanding of creative prompts |
No single tool dominates every dimension. Antigravity wins on context size and prototyping speed. Codex CLI wins on cost, transparency, and terminal workflows. Claude Code wins on raw coding accuracy and multi-surface availability. The right choice depends on which dimension matters most to your team and your codebase.
For developers who want to try the tools head-to-head: Antigravity’s free tier gives you 20 agent requests per day at no cost, Codex CLI is free to install with your own API key, and Claude Code is accessible through a Claude Pro subscription. All three have low enough entry barriers that hands-on evaluation is the fastest way to make your decision.
Disclosure: This article contains affiliate links. If you purchase a subscription through one of these links, we may earn a commission at no additional cost to you. We only recommend tools we have researched thoroughly. Benchmark data and pricing are sourced from official documentation and may change; verify current figures before purchasing.