OpenAI first introduced Codex on August 10, 2021, as a model that translated plain-English instructions into code and helped power GitHub Copilot. The original Codex models were retired in March 2023.
In April 2025, OpenAI revived Codex as an open-source coding agent for the terminal. A cloud agent followed in May, and subsequent releases expanded Codex to desktop and mobile apps, remote development, new coding models, and developer APIs.
This timeline records Codex release dates and major updates from 2021 onward.
Last updated: Oct 13, 2026.
Codex release timeline
2026: Codex models, apps, and CLI releases
October 2026
| Date | Release or change |
|---|---|
| Oct 11, 2026 | GPT-6.1 Sol gains a 500k-token default context The default GPT-6.1 Sol context in Codex and ChatGPT Work increased from 272,000 to 500,000 tokens, configurable up to one million. |
| Oct 9, 2026 | Composer predictions enter beta for personal Pro users Composer predictions entered beta on supported desktop threads for eligible personal Pro users. Suggestions could be accepted with Tab, edited, or ignored. |
| Oct 8, 2026 | Faster steering rolls out in the desktop app The desktop app began rolling out faster steering for running Codex tasks, with settings for immediate redirection or queued follow-up messages. |
| Oct 8, 2026 | GPT-6.1 Sol Ultrafast begins rolling out GPT-6.1 Sol Ultrafast began rolling out in Codex and Work for eligible plans. The Responses API also gained the ultrafast service tier. |
| Oct 8, 2026 | Codex CLI 0.162.0 Managed worktree tools, task pinning, transcript copying, and Code Mode tool search. |
| Oct 7, 2026 | Codex CLI 0.161.0 Bedrock multi-agent controls, live MCP login, voice preferences, and Daybreak opt-in. |
| Oct 6, 2026 | Auto-review becomes free for ChatGPT-signed-in users Auto-review stopped consuming plan usage for ChatGPT-signed-in sessions. A reviewer agent could handle eligible approval requests. |
| Oct 5, 2026 | Astra and Sol receive faster default inference Default inference speed increased by approximately 50% for GPT-6 Astra and GPT-6.1 Sol in the subscription experience. |
| Oct 1, 2026 | GPT-5.3-Codex API deprecation receives a shutdown date OpenAI deprecated the GPT-5.3-Codex API model and scheduled removal for April 1, 2027. The API change was distinct from model-picker access. |
September 2026
| Date | Release or change |
|---|---|
| Sep 29, 2026 | DevDay expands Codex cloud, review, and security DevDay introduced reusable Codex Cloud environments, redesigned pull-request reviews, hosted Codex Security Cloud scanning, Agents API computer use, and Astra Ultrafast. GitHub review reached general availability, and GitLab merge-request review entered preview. (Codex Cloud environments) |
| Sep 29, 2026 | GPT-6.1 Sol and Codex CLI 0.159.1 arrive GPT-6.1 Sol launched in Codex, Work, and the API. Codex CLI 0.159.1 included it as the default bundled model. (CLI 0.159.1) |
| Sep 29, 2026 | Codex CLI 0.159.0 Immediate steering during responses and long code-mode calls, plus transcript controls. |
| Sep 28, 2026 | Codex CLI 0.158.0 Full-screen copying, MCP OAuth client secrets, and bearer-token executor connections. |
| Sep 25, 2026 | Codex CLI 0.157.0 Full-screen transcripts, remote imports, and conversation forks across apps. |
| Sep 22, 2026 | GPT-6 Sol and Luna arrive in Codex GPT-6 Sol and Luna joined Codex and Work and became available through the API for different balances of coding capability and cost. |
| Sep 22, 2026 | Codex CLI 0.156.0 Voice by default, searchable full-screen UI, usage dashboard, and worktree sessions. |
| Sep 17, 2026 | Codex CLI 0.155.0 Experimental voice, task controls, Touch ID for local MCP, and daemon settings. |
| Sep 14, 2026 | GPT-5.5 retirement is announced for October 14 OpenAI announced GPT-5.5 retirement from ChatGPT, Work, and Codex for October 14, excluding the API. |
| Sep 14, 2026 | GPT-5.3-Codex-Spark research preview ends The GPT-5.3-Codex-Spark research preview ended in the desktop app, CLI, and IDE extension. |
| Sep 10, 2026 | Agents API opens the Codex harness to developers The Agents API entered public beta, exposing the managed Codex harness for durable sessions, context compaction, MCP, tool calling, and parallel subagents. Developers could use hosted or developer-managed execution environments. |
| Sep 10, 2026 | Data plugin Available in ChatGPT Work and Codex for connected data analysis and reports. |
| Sep 9, 2026 | GPT-6 Astra becomes available in Codex and the API GPT-6 Astra became available in Codex, Work, and the API. CLI 0.154.0 included it in the model picker and Bedrock catalogs. |
August 2026
| Date | Release or change |
|---|---|
| Aug 20, 2026 | Codex CLI 0.149.0 Agent task dashboard, queued messages, and stronger diagnostics. |
| Aug 18, 2026 | Codex CLI 0.148.0 Markdown export, session management, cost estimates, and Bedrock support. |
| Aug 11, 2026 | ChatGPT desktop ChatGPT Work and Codex share tasks from other agents. |
| Aug 11, 2026 | ChatGPT desktop Supported Linux desktop project and browser workflows. |
| Aug 7, 2026 | Codex CLI 0.147.0 Portable Agent Plugins, searchable catalogs, and import synchronization. |
July 2026
| Date | Release or change |
|---|---|
| Jul 29, 2026 | Codex CLI 0.146.0 Pinned sessions, plugin publishing, remote Code Mode, and web search. |
| Jul 28, 2026 | Security Codex Security CLI and SDK source released. |
| Jul 23, 2026 | Voice Direct multiple agents by voice in ChatGPT Work or Codex. |
| Jul 23, 2026 | Projects Related code and documentation can span multiple folders. |
| Jul 21, 2026 | Codex CLI 0.145.0 Paginated history, conversation imports, Bedrock login, and multi-agent work. |
| Jul 9, 2026 | GPT-5.6, ChatGPT desktop integration, and CLI 0.144.0 GPT-5.6 models joined Codex, and Codex entered the ChatGPT desktop app. The release also updated editing, review, and computer-use capabilities. |
| Jul 9, 2026 | Codex CLI 0.144.0 Write-approval mode, MCP authentication, and usage-credit details. |
| Jul 8, 2026 | Codex CLI 0.143.0 Remote plugins, proxy support, pairing, and Bedrock model routing. |
June 2026
| Date | Release or change |
|---|---|
| Jun 25, 2026 | Codex Remote reaches general availability Codex Remote reached general availability, connecting phones to Mac or Windows hosts for task supervision and approvals. |
| Jun 22, 2026 | Codex CLI 0.142.0 Usage credits, plugin recommendations, token budgets, and multi-agent controls. |
| Jun 18, 2026 | Codex CLI 0.141.0 Encrypted remote relays, plugin MCP servers, and import APIs. |
| Jun 2, 2026 | Sites and role-specific plugins Sites, role-specific plugins, and annotations arrived. Sites entered preview for Business and Enterprise workspaces. |
May 2026
| Date | Release or change |
|---|---|
| May 26, 2026 | older selectable models are deprecated GPT-5.3-Codex and GPT-5.2 left the model picker for ChatGPT-authenticated Codex sessions. API-key workflows were unaffected. |
| May 7 & 14, 2026 | Chrome, mobile, and Remote SSH Codex for Chrome arrived on May 7. Mobile preview and general availability for Remote SSH followed on May 14. |
April 2026
| Date | Release or change |
|---|---|
| Apr 16 & 23, 2026 | computer use and projectless chats April app updates introduced projectless chats, browser and computer use, Automations, artifact previews, and other task tools. |
March 2026
| Date | Release or change |
|---|---|
| Mar 25, 2026 | plugins package tools and workflows Codex plugins arrived across the app, CLI, and IDE extension, packaging reusable Skills, integrations, and MCP settings. |
| Mar 6, 2026 | Codex Security enters research preview The former Aardvark security agent became Codex Security and entered research preview for repository vulnerability investigation. |
| Mar 4 & 5, 2026 | Windows and GPT-5.4 The Codex app launched on Windows on March 4. GPT-5.4 joined Codex on March 5. |
February 2026
| Date | Release or change |
|---|---|
| Feb 5 & 12, 2026 | GPT-5.3-Codex and Spark GPT-5.3-Codex launched for agentic coding, followed by the low-latency Codex-Spark research preview on February 12. (GPT-5.3-Codex-Spark) |
| Feb 2, 2026 | the Codex app launches on macOS A dedicated Codex app launched on macOS with projects, parallel agents, worktrees, review tools, and shared session history. |
2025: Codex CLI and cloud agent launch
| Date | Release or change |
|---|---|
| Dec 18 & 19, 2025 | GPT-5.2-Codex and Agent Skills GPT-5.2-Codex launched December 18 for longer and more complex coding tasks. Reusable Agent Skills arrived the next day. |
| November 2025 | the GPT-5.1-Codex family expands GPT-5.1-Codex and Mini launched in November, followed by Codex-Max with support for longer sessions across multiple context windows. |
| Oct 6, 2025 | Codex reaches general availability Codex reached general availability with developer automation and team integrations, including an SDK and GitHub Action. |
| Sep 15, 2025 | GPT-5-Codex and the IDE extension arrive GPT-5-Codex launched for agentic software engineering alongside the IDE extension and a substantially updated CLI. |
| May 16, 2025 | Codex cloud enters research preview Codex Cloud entered research preview in ChatGPT. Each delegated coding task ran in its own repository-backed environment and could edit files, execute tests, and prepare changes for review. Early access reached Pro, Business, and Enterprise users, with Plus following in June. |
| Apr 16, 2025 | Codex CLI is released OpenAI launched the open-source Codex CLI, a coding agent that could inspect files, edit repositories, and execute commands locally. Approval and sandbox settings governed actions in the developer environment. |
2023: Original Codex model retirement
| Date | Release or change |
|---|---|
| March 2023 | OpenAI deprecates the Codex API models The original Codex API model family was retired after deprecation, concluding the first generation of OpenAI Codex. |
2021: Codex model introduction
| Date | Release or change |
|---|---|
| Aug 10, 2021 | Codex enters API private beta OpenAI opened a private beta for Codex, a GPT-3-descended code-generation model used in the early GitHub Copilot. The original model translated natural-language instructions into code and was distinct from the coding agent introduced in 2025. |
How Codex evolved from a model to a coding agent
The original Codex API model generated code from instructions supplied by an application. It did not manage a repository or execute a sequence of development tasks on its own. Applications built around the model decided which prompts to send and what to do with the generated code. GitHub Copilot was an early example of that model-based coding assistance.
Codex CLI and the cloud agent introduced a different work loop in 2025. The agent could inspect an existing codebase, make changes across files, execute commands, run tests, and revise its work after inspecting the results. Local sessions worked with the developer’s tools and Git state; cloud tasks used isolated environments prepared for the selected repository. Approval controls, sandbox restrictions, and reviewable changes became important parts of the product experience.
Later Codex releases extended this agent loop into editors, desktop projects, remote hosts, pull-request reviews, browser tasks, and team automations. Worktrees made it possible to keep parallel changes independent. The Agents API exposed the managed Codex harness to applications that needed durable sessions, tool calls, context compaction, MCP connections, and parallel agents. These changes expanded the kinds of tasks Codex could perform beyond generating code from a single prompt.
Codex model generations and major capability changes
The modern cloud agent initially used codex-1 for software-engineering tasks, while codex-mini-latest served lower-latency CLI and API work. GPT-5-Codex focused on an entire coding task, from reading a repository and editing files to running tools and responding to failures. GPT-5.1-Codex-Max introduced longer agent work across multiple context windows through context compaction, which helped with sustained debugging and large refactors.
The GPT-5.2-Codex and GPT-5.3-Codex generations expanded long-context work, tool use, Windows development, vision, and security-related tasks. GPT-5.3-Codex-Spark explored faster interactive coding. GPT-5.4 and GPT-5.5 continued the move toward general models used for both coding and other demanding tasks. The GPT-5.6 family introduced Astra, Sol, Terra, and Luna tiers across different capability and cost needs.
GPT-6 Astra extended long-running Codex work with asynchronous questions and an experimental context system for preserving earlier requirements and results. GPT-6 Sol and Luna expanded model options for different coding workloads, followed by GPT-6.1 Sol.
Where Codex runs
- Codex CLI runs in a local terminal and works with files, commands, Git, MCP servers, scripts, and non-interactive automation.
- The IDE extension places local sessions, diffs, and cloud task handoff inside VS Code, Cursor, and compatible editors.
- Codex Cloud runs delegated tasks in reusable managed environments with selected repositories, tools, and access settings.
- The ChatGPT desktop app manages projects, parallel threads, worktrees, reviews, terminals, Automations, browser tools, computer use, and plugins.
- The ChatGPT mobile app can start and supervise Codex work on connected local or remote hosts.
- The Agents API runs developer-built cloud agents on the managed Codex harness with OpenAI-hosted sandboxes, developer-managed infrastructure, or integrated sandbox providers.
- The SDK, GitHub Action, Slack integration, hooks, access tokens, and non-interactive CLI connect Codex with team systems and automation.
Codex FAQs
Is Codex free?
Codex has included free access for certain ChatGPT plans and features. In 2026, OpenAI expanded desktop access to Free and Go users and made Auto-review free for ChatGPT-signed-in sessions. Paid subscriptions have offered additional models and usage allowances. API-key usage is billed separately.
Does Codex run code locally?
Local Codex sessions can read files and run approved commands on the selected computer or SSH host. Sandbox rules, writable folders, and approval settings limit those actions. Codex cloud uses an OpenAI-managed environment. A cloud task receives only the files, dependencies, credentials, and services configured for that environment.
Is Codex CLI open source?
Yes. OpenAI publishes Codex CLI at github.com/openai/codex. The repository contains the agent implementation, installation instructions, source changes, and numbered releases. Hosted models and managed Codex services are separate from the open-source CLI code.
Does Codex require GitHub?
No. Codex CLI and the desktop app can work with local folders and Git repositories without a GitHub connection. GitHub is important for cloud repository tasks, pull requests, code review, and the GitHub Action. A local session can also use another Git host through ordinary command-line tools if the environment has access.
Is there a Codex API?
Yes. OpenAI released the Agents API in public beta on September 10, 2026. It exposes the managed harness behind Codex and handles orchestration, long-running sessions, context compaction, and recovery. Developers choose the model, tools, and execution environment and can connect MCP servers, custom functions, and built-in tools. The Agents API also supports computer use. It has no additional platform fee. Model token and tool charges apply. The Codex SDK and non-interactive CLI provide separate automation options.
Can Codex use browser pages and desktop applications?
Supported Codex app versions can operate an in-app browser and use desktop applications through computer use. The Chrome extension can supply signed-in browser context for approved sites. Availability depends on the operating system, region, plan, administrator controls, installed plugin, and permission settings.
When did GPT-6 Astra arrive in Codex?
OpenAI announced GPT-6 Astra availability in Codex and the API on September 9, 2026. Codex CLI 0.154.0 included Astra in the model picker and Amazon Bedrock catalogs.
When were GPT-6 Sol and Luna released for Codex?
GPT-6 Sol and GPT-6 Luna arrived in Codex and the API on September 22, 2026. GPT-6.1 Sol followed on September 29, 2026, along with Codex CLI 0.159.1.
Sources
Related AI timelines and resources
- Claude Code Timeline: Release Date and Major Updates
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