# Alternatives to OpenAI Codex

> Source: https://theagentsindex.com/openai-codex/alternatives/ (re-verified)
> Updated: 31 October 2026

## At a glance

| Name | Best for | Starts at | Better than OpenAI Codex at | Checked |
| --- | --- | --- | --- | --- |
| [OpenAI Codex](https://theagentsindex.com/openai-codex.md) | Developers who want one coding agent in their terminal, IDE and the cloud | From $8 a month | — | 24 October 2026 |
| [Factory](https://theagentsindex.com/factory-ai.md) | Engineering organizations that want AI agents handling more of the SDLC than code generation alone (triage, testing, release and documentation) and are willing to pay enterprise pricing for deployment flexibility and compliance controls. | From $20 a month | Whole-codebase work, Runs autonomously | 2 September 2026 |
| [Google Antigravity CLI](https://theagentsindex.com/antigravity-cli.md) | Developers already inside the Google ecosystem (Google AI subscription, GCP billing) who want a free terminal agent with Gemini, Claude and gpt-oss model access, especially anyone migrating off a now-sunset Gemini CLI workflow. | Free, then $30 a seat a month | Whole-codebase work, Pooled budget | 22 October 2026 |
| [Junie](https://theagentsindex.com/junie.md) | Developers and teams already standardized on a JetBrains IDE who want an agent that shares the same debugger, project index, and version control already built into their editor. | Free, then about $11 a seat a month | Whole-codebase work, Runs autonomously | 18 September 2026 |
| [Muse Code](https://theagentsindex.com/muse-code.md) | Cost-sensitive teams willing to trade code privacy for Contributor tier's roughly 12x cheaper input and 21x cheaper output, or anyone with a large multi-part refactor that benefits from several sub-agents working in parallel isolated worktrees. | From $5 a month | Runs autonomously, Pooled budget | 20 September 2026 |
| [OpenCode](https://theagentsindex.com/opencode.md) | Developers who want a genuinely free, fully open-source coding agent that works with any model provider, including their own local Ollama models, without being locked into one vendor's terminal tool. | Free, then $10 a month | Runs autonomously, Model choice | 21 October 2026 |
| [Cursor](https://theagentsindex.com/cursor.md) | Professional developers who want a powerful AI agent woven into a familiar VS Code-based editor, with first-class model choice and the option to be hands-off via Cursor Router. | Free, then $8 a month | Whole-codebase work, Runs autonomously | 2 September 2026 |
| [Letta](https://theagentsindex.com/letta.md) | Developers and researchers who specifically need an agent whose memory, skills and identity genuinely persist and evolve across long-running sessions, rather than reset on every call. | Free, then $20 a month | Runs autonomously, Model choice | 2 September 2026 |
| [Aider](https://theagentsindex.com/aider.md) | Developers who want free, model-agnostic AI pair programming in their terminal | Free | Runs autonomously, Model choice | 27 October 2026 |
| [Devin](https://theagentsindex.com/devin.md) | Engineering teams offloading well-scoped migration tasks without adding headcount | Free, then $20 a month | Whole-codebase work, Runs autonomously | 2 September 2026 |

“About” figures are converted at the European Central Bank rate of 30 October 2026.

## What to watch for

- **Factory**: No free tier or trial — the cheapest plan is $20/month.
- **Google Antigravity CLI**: Not yet open source. No LICENSE file in its public GitHub repo, unlike the Apache-2.0 Gemini CLI it replaces, and Google has not confirmed whether that will change.
- **Junie**: Credit-based pricing shared across all JetBrains AI features makes the effective monthly cost of regular agentic use harder to predict than a flat subscription.
- **Muse Code**: Three observer agents (memory, skill, goal) run by default and add their own billed model calls on top of the main session, switchable in settings.json under runtime_capabilities.
- **OpenCode**: The web UI's server-URL-override feature and local HTTP server have a real, disclosed 2026 security history (two now-patched advisories), so running it on a shared or untrusted network needs care.
- **Cursor**: No first-class headless or CI mode. Cursor is an interactive editor with a CLI and background agents, not a scriptable terminal agent in the same mould as Claude Code or Codex CLI.
- **Letta**: Smaller ecosystem and community than LangChain, LlamaIndex or Microsoft AutoGen.
- **Aider**: Usage numbers like 44K GitHub stars, 6.8M installs, 15B tokens/week and the 88% 'Singularity' metric are self-reported on aider.chat; independent verification of these figures was not found.
- **Devin**: Independent real-world testing has found success rates around 15% on a 20-task sample, well below the roughly 45.8% Devin 2.0 reports on SWE-bench Verified, so performance varies significantly by task type and spec quality.

The ones people open most here come first, then the closest matches.

## Shortlist

### 1. Factory

Droid coding agents that run in the desktop app, CLI, IDEs, CI and Factory-managed cloud computers.

**Where it improves on OpenAI Codex:**
- [Whole-codebase work: yes — Missions decompose multi-feature work into milestones and are documented for brownfield migrations.](https://docs.factory.ai/missions/overview)
- [Runs autonomously: yes — Headless droid exec runs one-shot tasks to completion; Missions orchestrate long multi-feature work.](https://docs.factory.ai/droid-exec/overview)
- [Model choice: yes — You pick the model per session, per subagent and per exec run with -m/--model, or add custom endpoints.](https://docs.factory.ai/droid-exec/overview)

**Trade-offs against OpenAI Codex:**
- [Free tier: no — Every priced plan on the page is paid: the ladder runs 01 Pro at $20/mo to 06 Enterprise, with no $0 tier and no trial named anywhere on it, so the cheapest way in is a self-serve $20 monthly subscription. Free usage appears only inside paid plans - a BYOK allowance and a free switch to Droid Core after a rate limit.](https://factory.com/pricing)
- [Admin controls: partial — Org-managed settings cap autonomy and restrict models, MCP servers, commands and network; listed from Business upward, with full controls on Enterprise.](https://factory.com/pricing)
- [Single sign-on: partial — SAML/OIDC SSO with SCIM directory sync via WorkOS, sold from the Business plan; Teams and individual plans have none.](https://docs.factory.ai/enterprise/identity-and-access)

[View Factory](https://theagentsindex.com/factory-ai)

### 2. Google Antigravity CLI

Terminal agent (agy) that runs Google Antigravity coding agents and parallel subagents.

**Where it improves on OpenAI Codex:**
- [Whole-codebase work: yes — The vendor frames long-running CLI sessions around repository-wide work such as subsystem refactors and dependency migrations, not single-file edits.](https://antigravity.google/docs/remote-control?tab=cli)
- [Pooled budget: yes — Gemini Enterprise Standard and Plus pool first-party model credits across edition seats for Antigravity use.](https://antigravity.google/docs/enterprise)

**Trade-offs against OpenAI Codex:**
- [Reviews code: partial — The diff viewer opens workspace changes, agent turns and any commit in the repository for line-level comments, but review is a human reading diffs to steer the agent; no pull-request or reviewer workflow is documented.](https://antigravity.google/docs/cli/commands/diff)
- [Agent permissions: partial — A three-list allow/ask/deny engine governs files, commands, URLs and MCP tools, but unconfigured actions default to asking, so broad autonomy requires rules you write yourself.](https://antigravity.google/docs/permissions)
- [GPT: partial — No OpenAI GPT model is offered; the only GPT-named entry is the open-weight GPT-OSS-120b, which the table marks for removal and excludes from Enterprise.](https://antigravity.google/docs/models)

[View Google Antigravity CLI](https://theagentsindex.com/antigravity-cli)

### 3. Junie

JetBrains coding agent for the terminal, JetBrains IDEs and CI, running on hosted or your own model keys.

**Where it improves on OpenAI Codex:**
- [Whole-codebase work: yes — The vendor claims repository-wide edits rather than single-file assistance, and markets long-running migrations specifically as the case its asynchronous remote mode exists for.](https://www.jetbrains.com/help/ai-assistant/junie-agent.html)
- [Runs autonomously: yes — It completes multi-step tasks unattended, and a brave mode removes the approval prompts entirely; headless CI runs and GitHub Action triggers have no human in the loop at all.](https://www.jetbrains.com/help/ai-assistant/junie-agent.html)
- [Model choice: yes — You choose, not the vendor: four provider classes are supported and a flag forces a specific one, though leaving the default lets JetBrains pick on price-quality grounds.](https://junie.jetbrains.com/docs/junie-cli-model-selection.html)

**Trade-offs against OpenAI Codex:**
- [In a browser: partial — The web app is a companion view onto a CLI session still running on your own machine, not a standalone hosted agent, and the vendor lists a dozen features it cannot do.](https://junie.jetbrains.com/docs/junie-cli-remote-mode.html)
- [Open source: no — The public repository carries installers, model profiles and a plugin rather than agent source, and its licence section reserves all rights and points at proprietary service terms.](https://github.com/JetBrains/junie)
- [Admin controls: partial — A developer can constrain the agent locally through the allowlist file on any tier, but organisation-wide policy such as company MCP rules is an enterprise capability.](https://www.jetbrains.com/ide-services/ai-enterprise/)

[View Junie](https://theagentsindex.com/junie)

### 4. Muse Code

Meta's terminal and CI coding agent, built on the Muse Spark model.

**Where it improves on OpenAI Codex:**
- [Runs autonomously: yes — A headless run takes one prompt to completion with approvals disabled, and session goals keep the runtime queueing follow-up work until the objective is met.](https://dev.meta.ai/docs/muse-code/extending)
- [Pooled budget: yes — Rate and token quotas are shared across the whole team rather than allocated per key, so multiple developers draw on one pool on pay-as-you-go.](https://dev.meta.ai/docs/pricing-rate-limits)
- [Opt out of training: yes — Standard-tier models are contractually excluded from training, and the discounted contributor models that do train on your content are opt-in by model id and can be left behind by upgrading.](https://dev.meta.ai/legal/commitments)

**Trade-offs against OpenAI Codex:**
- [Reviews code: partial — Review happens inside its own runs — background reviewer and verification agents check the work — rather than as a review of a diff someone else wrote in a pull request.](https://dev.meta.ai/lp/muse-code)
- [GPT: no — Same closed model enumeration: only the two Muse Spark 1.2 model IDs are selectable; OpenAI compatibility is SDK shape, not an OpenAI model.](https://developer.meta.com/ai/products/muse-code/)
- [In your editor: no — The vendor describes exactly two run surfaces, interactive terminal and headless, with no editor or IDE extension mentioned anywhere in the Muse Code documentation set.](https://dev.meta.ai/docs/muse-code)

[View Muse Code](https://theagentsindex.com/muse-code)

### 5. OpenCode

Open source AI coding agent for the terminal, desktop, IDE and browser, with any LLM provider.

**Where it improves on OpenAI Codex:**
- [Runs autonomously: yes — An auto-approve mode clears every permission prompt that is not explicitly denied, and non-interactive runs plus scheduled GitHub workflows execute with no one watching.](https://opencode.ai/docs/permissions/)
- [Model choice: yes — You pick the model per session or per agent in provider/model form; the vendor's own gateway is explicitly optional rather than a default lock-in.](https://opencode.ai/)
- [Self-hosted: yes — The agent runs on your own machine or server with no vendor backend in the path, and enterprises can point it at an internal AI gateway only.](https://opencode.ai/docs/enterprise/)

**Trade-offs against OpenAI Codex:**
- [Seat model: partial — The gateway charges no seat fee at any team size, so seats only appear in the unpriced enterprise agreement, which is quoted rather than published.](https://opencode.ai/docs/enterprise/)

[View OpenCode](https://theagentsindex.com/opencode)

### 6. Cursor

Coding agent in a desktop editor, terminal CLI, cloud VMs and CI, priced per seat plus token usage.

**Where it improves on OpenAI Codex:**
- [Whole-codebase work: yes — Cloud agents work across multiple repositories in one task and raise a pull request in each repo they touch.](https://cursor.com/docs/cloud-agent)
- [Runs autonomously: yes — Tasks complete without a human in the loop; /goal keeps the agent working towards an objective, and cloud agents run with the laptop closed.](https://cursor.com/docs/agent/overview)
- [Model choice: yes — You pick the model per request, or hand selection to Auto/Cursor Router; each choice bills at that model's own rate.](https://cursor.com/docs/models-and-pricing)

**Trade-offs against OpenAI Codex:**
- [Open source: no — The Terms of Service forbid deriving or accessing the source; the /licenses page covers only third-party open source components used inside the IDE.](https://cursor.com/terms-of-service)
- [Admin controls: partial — Teams admins enforce Privacy Mode, team rules and sandbox mode; repository blocklists, model/MCP access controls and auto-run, browser and network controls are Enterprise-only.](https://cursor.com/pricing)
- [Single sign-on: partial — SAML 2.0 at no extra cost on Teams and Enterprise, advertised as SAML/OIDC on the plan card; SCIM provisioning is Enterprise-only and individual plans have no SSO.](https://cursor.com/help/security-and-privacy/sso)

[View Cursor](https://theagentsindex.com/cursor)

### 7. Letta

Stateful agent harness, cloud and SDK for agents with persistent, git-versioned memory.

**Where it improves on OpenAI Codex:**
- [Runs autonomously: yes — Headless CLI runs, scheduled prompts and subagents execute without a human turn; unrestricted mode auto-allows tools.](https://docs.letta.com/configuration/subagents/index.md)
- [Model choice: yes — You pick the model and can switch mid-conversation; memory travels with the agent across providers.](https://docs.letta.com/configuration/models/index.md)
- [Self-hosted: yes — Local runtime keeps all state on-device with no account, or run the App Server via Docker, Railway or Fly.io.](https://docs.letta.com/self-hosting/index.md)

**Trade-offs against OpenAI Codex:**
- [Writes tests: partial — Vendor claims agents run test suites; it never claims they author tests.](https://docs.letta.com/handbook/index.md)
- [MCP server: no — MCP runs inbound only: Letta sessions consume stdio, HTTP and SSE MCP servers; no Letta MCP server is published.](https://docs.letta.com/agent-sdk/mcp/index.md)
- [Seat model: partial — Priced per seat on Teams Pro; no seat minimum or maximum is published, and Enterprise seat pricing is by contact.](https://docs.letta.com/pricing/index.md)

[View Letta](https://theagentsindex.com/letta)

### 8. Aider

Open-source terminal AI pair programmer that edits your local git repo.

**Where it improves on OpenAI Codex:**
- [Runs autonomously: yes — A single --message run applies the edits and exits with no interaction, and --yes suppresses every confirmation, which is how the vendor documents scripted unattended use.](https://aider.chat/docs/scripting.html)
- [Model choice: yes — You choose the model with --model and the vendor claims connection to almost any LLM, including local ones; it only warns that weaker models edit files badly.](https://aider.chat/)
- [Self-hosted: yes — Aider installs and runs entirely on your own machine as a local Python tool; there is no vendor-hosted runtime between you and your files.](https://aider.chat/docs/install.html)

**Trade-offs against OpenAI Codex:**
- [Multi-agent: partial — Architect mode splits one task between two models, a planner and an editor, but that is a fixed two-model pipeline rather than several agents coordinating freely.](https://aider.chat/docs/usage/modes.html)
- [In your pipeline: partial — Non-interactive runs are scriptable from a shell loop with --message and --yes, but nothing on the site documents acting on a pull request or a hosted CI integration.](https://aider.chat/docs/scripting.html)
- [In a browser: partial — A browser UI exists but the vendor labels it experimental, and it is a local server you start yourself rather than a hosted web product.](https://aider.chat/docs/usage/browser.html)

[View Aider](https://theagentsindex.com/aider)

### 9. Devin

Cloud AI software engineer that takes a ticket, works in its own VM, and opens a pull request.

**Where it improves on OpenAI Codex:**
- [Whole-codebase work: yes — Migrations spanning many files, modules or whole repositories are the stated use for fanning work out to parallel sessions.](https://docs.devin.ai/work-with-devin/advanced-capabilities)
- [Runs autonomously: yes — Automations and schedules start sessions from events, so Devin works the task with nobody tagging it.](https://docs.devin.ai/product-guides/automations)
- [MCP server: yes — An authenticated MCP server at mcp.devin.ai lets any MCP client create sessions, query repositories and manage playbooks.](https://docs.devin.ai/work-with-devin/devin-mcp)

**Trade-offs against OpenAI Codex:**
- [Bring your own key: partial — Your own AWS KMS key encrypts data at rest, but only on the Enterprise Assured deployment; no bring-your-own-inference is documented.](https://docs.devin.ai/enterprise/security-access/security/customer-managed-keys)
- [Single sign-on: partial — SAML 2.0 and OIDC (Okta, Microsoft Entra ID, generic) on Devin Enterprise, configured by the Cognition team, with IdP group to role mapping.](https://docs.devin.ai/enterprise/security-access/sso/guide)

[View Devin](https://theagentsindex.com/devin)