Gemini Antigravity vs ChatGPT 5.1 Codex: Which AI Coding System Is Better for Tools, Pricing, and Performance?

Graziano Stefanelli
1 hour ago
4 min read

Gemini Antigravity and ChatGPT 5.1 Codex represent two of the most advanced approaches to AI-assisted software development. Both tools were designed to move beyond simple code completion and into full agentic engineering, where the AI can plan tasks, modify multiple files, interpret errors, run commands, and maintain long-running sessions.

Yet the two systems come from very different philosophies. Antigravity is a Google-built AI IDE built around Gemini 3 Pro and a multi-agent workspace, while GPT-5.1 Codex is OpenAI’s specialized coding model that powers GitHub Copilot, agent workflows, and tool-driven coding harnesses.

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Antigravity is an AI-first IDE built around agents that operate the editor, terminal, and browser.

Where ChatGPT 5.1 Codex provides a coding engine, Antigravity provides a full environment. The difference is structural:

Antigravity includes:

• an Editor View for coding with agent assistance

• a Manager View where the developer can orchestrate multiple agents

• a built-in browser agents can control for research, scraping, and testing

• a terminal agents can use to run commands, tests, installs, and deployments

• an “Artifact” system for tracking each agent’s actions—plans, logs, screenshots, recordings

• a built-in Gemini 3 Pro model orchestrating long tasks

This makes Antigravity feel like a “mission control room” for development, where AI performs tool-level actions transparently and leaves behind a complete audit trail.

By contrast, Codex expects developers to bring their own editor (VS Code, JetBrains, Xcode, etc.) and integrate the model through chat, agent modes, and tool calls.

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ChatGPT 5.1 Codex is a specialized coding model tuned for long-running, multi-file engineering tasks.

GPT-5.1 Codex is not an IDE — it’s the model that powers advanced coding workflows inside GitHub Copilot and other agent frameworks.

It is optimized for:

• multi-file repository refactoring

• precise diffs with apply_patch

• test-driven debugging loops

• long-running sessions requiring memory of code context

• analyzing logs, compiler errors, and stack traces

• consistent multi-step iteration through codebases

GPT-5.1 Codex is trained to behave like a dependable senior engineer inside tool-driven environments. It writes smaller, safer diffs; it navigates real repositories; it avoids unnecessary rewrites; and it interprets test outputs with high accuracy.

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Structural Comparison: IDE vs. Model

Dimension	Gemini Antigravity	ChatGPT 5.1 Codex
Product Type	AI-first IDE workspace	Specialized coding model
Model Backbone	Gemini 3 Pro	GPT-5.1 Codex / Codex-Mini
Tool Integration	Editor, terminal, browser	apply_patch, shell, custom tools
Auditability	Artifact system logs actions	Tool-call logs via IDE
Primary Use	Agentic multi-agent development	Repo-level engineering tasks
Flexibility	Full workspace	Works inside any IDE via Copilot

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Gemini 3 Pro leads on multimodal reasoning, but Codex leads in code reliability inside repositories.

Gemini 3 Pro, the engine behind Antigravity, consistently ranks at the top of broad reasoning and multimodal benchmarks. It excels in tasks requiring image understanding, document analysis, and conceptual planning.

This benefits Antigravity when:

• combining text, images, UI elements, and research

• generating plans, architectures, and cross-file strategies

• performing agent-level reasoning before coding

However, GPT-5.1 Codex is designed to outperform generalist models in structured engineering environments. It tends to produce:

• cleaner diffs

• safer file edits

• more stable long sessions

• fewer accidental overwrites or hallucinated imports

The trade-off is clear: Gemini 3 Pro is a broader thinker; Codex is a more precise engineer.

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Model Capability Comparison

Category	Gemini 3 Pro (Antigravity)	GPT-5.1 Codex
General Reasoning	Excellent	Excellent
Multimodality	Strong (vision, audio, web)	Strong but text-centered
Repo-Level Editing	Moderate	Superior
Long Debugging Loops	Improving	Very reliable
Architecture Planning	Outstanding	Very strong
Code Precision	Good	Excellent
Task Decomposition	Excellent	Excellent

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Antigravity gives developers a cockpit of multiple agents, while Codex integrates seamlessly into existing workflows.

A major difference lies in how developers interact with the system:

Antigravity

You orchestrate multiple AI agents that can:

• write code

• run commands

• browse the web

• generate artifacts

• maintain multi-window contexts

This design is powerful but can be unpredictable in early preview builds. Agents may loop, reach invisible quotas, or mis-handle long sessions depending on the project size.

ChatGPT 5.1 Codex

Works through:

• GitHub Copilot (Chat, Edit, Agent modes)

• Codex-like tool harnesses with structured tool calls

• apply_patch for safe diffs

• shell tools for tests and commands

The Codex workflow is more traditional — less flashy, more stable — and deeply optimized for real-life repositories.

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Pricing: Antigravity is free in preview, while Codex follows OpenAI and Copilot pricing models.

Pricing differs widely:

Gemini Antigravity

• Free in public preview

• Uses “generous rate limits”

• Based on Gemini 3 Pro token costs once billing goes live

• Team and enterprise use expected to incur charges

• Likely integration with Google AI Pro/Ultra subscription tiers

ChatGPT 5.1 Codex

• API token pricing (GPT-5.1 tier)• GitHub Copilot subscription models:

Copilot Individual
Copilot Pro / Pro+
Copilot Business
Copilot Enterprise

Codex is predictable and mature; Antigravity pricing is early and evolving.

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Pricing Structure Overview

Product	Current Cost	Future Cost Expectation
Antigravity	Free preview	Token billing + subscription
Gemini 3 Pro	API token model	Same
GPT-5.1 Codex	API token model	Same
Copilot (Codex backend)	Monthly subscription	Stable

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Which system is better depends on the workflow: research-heavy vs. repository-heavy development.

If your development requires:

• heavy reasoning

• research and browsing

• agents operating multiple tools

• rapid prototyping with artifacts

• multimodal context input

• conceptual or architectural generation

Then Gemini Antigravity currently feels more dynamic and exploratory.

If your work depends on:

• maintaining large repositories

• stable, small diffs

• production-grade debugging

• long test-driven loops

• reliable multi-file modifications

• deep integration with existing IDEs

Then ChatGPT 5.1 Codex is the more dependable choice today.

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Gemini Antigravity and ChatGPT 5.1 Codex represent two powerful but fundamentally different approaches to AI-assisted coding. Antigravity offers a futuristic multi-agent IDE built on top of Google’s strongest reasoning model, while Codex provides a grounded, highly reliable model for real repository engineering through normalized developer tools. In practice, Antigravity is ideal for ideation and exploratory workflows, while Codex dominates stability, precision, and software production work.

As both ecosystems evolve, developers will likely use each tool strategically: Antigravity for creative engineering and Gemini-level planning, Codex for long-term maintainability and safe code execution inside real repositories.

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DATA STUDIOS

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[datastudios.org]