Top 9 of 31 alternatives
9 OpenAI Codex alternatives, 7 with a free plan (2026)
The closest alternatives to OpenAI Codex in October 2026 are Factory, Google Antigravity CLI and Junie. OpenAI Codex is from $8 a month. Muse Code has the lowest paid plan here, from $5 a month.
9 agents compared · entry plans $5 to $20 a month · 7 with a free plan · prices checked 21 October–1 November 2026
Reviewed by The Agents Index editorial team.
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OpenAI Codex and its alternatives at a glance
| Agent | Best for | Starts at | Better than OpenAI Codex at | Checked |
|---|---|---|---|---|
| OpenAI Codex | Developers who want one coding agent in their terminal, IDE and the cloud | From $8 a month source | 24 October 2026 | |
| Factory | 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 source | Whole-codebase work, Runs autonomously | 2 September 2026 |
| Google Antigravity CLI | 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 source | Whole-codebase work, Pooled budget | 22 October 2026 |
| Junie | 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 source | Whole-codebase work, Runs autonomously | 18 September 2026 |
| Muse Code | 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 source | Runs autonomously, Pooled budget | 20 September 2026 |
| OpenCode | 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 source | Runs autonomously, Model choice | 21 October 2026 |
| Cursor | 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 source | Whole-codebase work, Runs autonomously | 2 September 2026 |
| Letta | 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 source | Runs autonomously, Model choice | 2 September 2026 |
| Aider | Developers who want free, model-agnostic AI pair programming in their terminal | Free source | Runs autonomously, Model choice | 27 October 2026 |
| Devin | Engineering teams offloading well-scoped migration tasks without adding headcount | Free, then $20 a month source | Whole-codebase work, Runs autonomously | 2 September 2026 |
“About” figures are converted at the European Central Bank rate of 30 October 2026.
Closest alternatives to OpenAI Codex
The ones people open most here come first, then the closest matches. How we check
- From $20 a month
Droid coding agents that run in the desktop app, CLI, IDEs, CI and Factory-managed cloud computers.
Why it's on this listWhole-codebase work: YesMissions decompose multi-feature work into milestones and are documented for brownfield migrations.
Watch forNo free tier or trial — the cheapest plan is $20/month.
- From Free
Terminal agent (agy) that runs Google Antigravity coding agents and parallel subagents.
Why it's on this listWhole-codebase work: YesThe vendor frames long-running CLI sessions around repository-wide work such as subsystem refactors and dependency migrations, not single-file edits.
Better than OpenAI Codex at- Pooled budget: Yes ↗
Watch forNot 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.
- From Free
JetBrains coding agent for the terminal, JetBrains IDEs and CI, running on hosted or your own model keys.
Why it's on this listWhole-codebase work: YesThe 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.
Watch forCredit-based pricing shared across all JetBrains AI features makes the effective monthly cost of regular agentic use harder to predict than a flat subscription.
The rest of the shortlist
- From $5 a month
Muse Code
Meta's terminal and CI coding agent, built on the Muse Spark model.
Watch for: 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.
- From Free
OpenCode
Open source AI coding agent for the terminal, desktop, IDE and browser, with any LLM provider.
Watch for: 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.
- From Free
Cursor
Coding agent in a desktop editor, terminal CLI, cloud VMs and CI, priced per seat plus token usage.
Watch for: 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.
- From Free
Letta
Stateful agent harness, cloud and SDK for agents with persistent, git-versioned memory.
Watch for: Smaller ecosystem and community than LangChain, LlamaIndex or Microsoft AutoGen.
- From Free
Aider
Open-source terminal AI pair programmer that edits your local git repo.
Watch for: 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.
- From Free
Devin
Cloud AI software engineer that takes a ticket, works in its own VM, and opens a pull request.
Watch for: 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.
Compare OpenAI Codex with the shortlist
Compare alternatives to OpenAI Codex
The digest
Which agents actually ship. New agents and articles, by email, at most once a week.
Questions buyers ask
What are the best alternatives to OpenAI Codex?
Factory, Google Antigravity CLI and Junie are the closest. They share the most of OpenAI Codex's features.
What is the cheapest alternative to OpenAI Codex?
7 of the 9 have a free plan: Google Antigravity CLI, Junie, OpenCode, Cursor and Letta and 2 more. The lowest paid plan is Muse Code, from $5 a month. Price checked on 28 October 2026.
When were these prices checked?
Between 21 October 2026 and 1 November 2026, each read on the maker's own pricing page.
Sources and method
Closest first: most of OpenAI Codex's features, then the fewest gaps. How we check
Every price here was read on the maker's own pricing page.
- OpenAI Codex: learn.chatgpt.com/docs/pricing, checked 24 October 2026
- Factory: factory.com/pricing, checked 24 October 2026
- Google Antigravity CLI: antigravity.google/pricing, checked 30 October 2026
- Junie: jetbrains.com/store/ai, checked 1 November 2026
- Muse Code: dev.meta.ai/products/muse-code, checked 28 October 2026
- OpenCode: opencode.ai/v2/docs, checked 21 October 2026
- Cursor: cursor.com/pricing, checked 31 October 2026
- Letta: docs.letta.com/pricing, checked 1 November 2026
- Aider: aider.chat/docs/faq.html, checked 27 October 2026
- Devin: devin.ai/pricing, checked 24 October 2026
What changed in the index
Agents we’ve just listed and every plan whose price changed.