Codex vs smol developer: How They Actually Differ
Choose Codex if you need a coding agent that moves among the terminal, IDE, desktop, and cloud, and reviews GitHub pull requests. Choose smol developer if you want an open-source, single-prompt, multi-file project scaffold from the command line and will supply your own LLM provider credentials.
Compiled 2026-08-27 from our catalogue entries for Codex and smol developer.
The short answer
- Pick Codex if
- You want one agent across the CLI, IDE extension, desktop app, and cloud, including GitHub pull-request review.
- Pick smol developer if
- You want an open-source CLI for a one-sentence brief that produces a full multi-file project scaffold, and you will bring your own LLM credentials.
- Cheapest way in
- Codex lists a Free plan at $0 per month. smol developer is listed as Free, but it requires the user to supply and pay for their own LLM API keys.
- What we could not compare
- The fact sheet has no verified plans on file for smol developer, and Codex's Business/Enterprise pricing is not published.
Codex is an AI coding agent with freemium pricing. It runs on OpenAI's GPT models, with GPT-5.5 listed as the recommended frontier model, and is included with ChatGPT plans from the free tier through Pro. It reads AGENTS.md, supports MCP tools, and can review GitHub pull requests in the cloud.
smol developer is a free, open-source CLI tool across macOS, Windows, and Linux. It takes a one-sentence natural-language brief and generates a full multi-file project scaffold using the user's own LLM provider credentials. Its primary interface is the CLI, with no first-party IDE or web UI; users pay for the LLM API keys they supply.
Side by side
Every cell is a field on our catalogue entry for that tool, copied as recorded. Rows where the two differ come first; blank fields say so rather than being filled in.
| Codex | smol developer | |
|---|---|---|
| Pricing model | Freemium | Free |
| Starts at | Free — $0 /month | Free |
| Runs on | web, mac, win, linux, cli, vscode-ext | mac, win, linux, cli |
| Public source code | No public repo listed | Yes — public repo |
| Category | AI Coding Agents | AI Coding Agents |
| Public docs | Not listed | Not listed |
- Public source code: From the repository link on each catalogue entry, not a licence audit.
Where Codex is the better fit
- Runs the same agent across the terminal CLI, IDE extension, desktop app, and cloud, with work able to continue across those surfaces.
- Provides cloud code review for GitHub pull requests, with inline comments and proposed fixes.
- Reads AGENTS.md, supports MCP tools, and is included with ChatGPT plans from the free tier through Pro.
Where smol developer is the better fit
- Open-source project with a public repository listed; it can be self-inspected and modified.
- Generates a full multi-file project scaffold from a single natural-language brief.
- Works from the command line on macOS, Windows, and Linux, with a bring-your-own-key model for LLM provider credentials.
Which one should you pick?
The Free plan is listed at $0 per month, and Codex is included with ChatGPT plans from the free tier through Pro.
Codex can run cloud code review for GitHub pull requests and runs the same agent across those surfaces.
It turns a one-sentence brief into a full multi-file project scaffold and is open source.
It is an open-source project with a listed public repository, and the fact sheet says it can be self-inspected and modified.
Frequently asked questions
- What is smol developer's pricing model?
- The pricing model is free; no verified plans are on file. It requires the user to supply and pay for their own LLM API keys.
- Can Codex review GitHub pull requests?
- Yes. It can run a cloud code review on a GitHub pull request, comment inline, and propose fixes.
- Does smol developer have a first-party IDE or web UI?
- No. Its primary interface is the CLI, and the fact sheet records no first-party IDE or web UI.
- What is Codex's model limitation?
- It is locked to OpenAI's GPT models; Claude or Gemini are not available out of the box.
What we compared
This page states nothing that is not in the two catalogue entries below. The exact text used to write it is reproduced here so you can check our reading, and both tools link through to their own pages and to the vendor.
- /tools/codex — checked 2026-07-02 · official site
- /tools/smol-developer — checked 2026-06-14 · official site
Show the source text
## Codex (/tools/codex) Tagline: OpenAI's coding agent — works in the terminal, IDE, and cloud, reviews GitHub pull requests, and runs on GPT-5 models. Category: AI Coding Agents Pricing model: freemium Starts at: Free — $0 /month Platforms: web, mac, win, linux, cli, vscode-ext Public repo: none listed Docs: none listed Verified plans (read 2026-08-21): Free $0 /month | Go $8 /month | Plus $20 /month | Pro 5x $100 /month | Pro 20x $200 /month | Business / Enterprise Not published | API Key Pay only for the tokens Codex uses, based on API pricing Strengths on file: Runs one agent across CLI, IDE, desktop, and cloud — work moves between surfaces.; Strong GitHub integration: a cloud code review on a pull request that catches real bugs and proposes fixes.; Reads the shared AGENTS.md standard and supports MCP tools.; Included with ChatGPT plans, from the free tier up through Pro. Limits on file: Locked to OpenAI's GPT models — no Claude or Gemini out of the box.; Fewer built-in customization primitives (hooks, sub-agents) than some rivals. Codex is OpenAI's agentic coding tool. It runs the same agent across a terminal CLI, an IDE extension, a desktop app, and a cloud environment, so work started in one surface can continue in another. It reads the shared AGENTS.md instructions file, speaks the Model Context Protocol (MCP), and can spin up a cloud code review on a GitHub pull request that comments inline and proposes fixes. Codex runs on OpenAI's GPT models — currently GPT-5.5 as the recommended frontier model — and is included with ChatGPT plans, from the free tier up through Pro. ## smol developer (/tools/smol-developer) Tagline: Single-prompt full-app generator that builds a project from a one-sentence brief. Category: AI Coding Agents Pricing model: free Starts at: Free Platforms: mac, win, linux, cli Public repo: https://github.com/smol-ai/developer Docs: none listed Verified plans: none on file Strengths on file: Open-source project that can be self-inspected and modified.; Operates from the command line across macOS, Windows, and Linux.; Uses a bring-your-own-key model so users connect their own LLM provider credentials.; Generates a full multi-file project scaffold from a single natural-language brief. Limits on file: Requires the user to supply and pay for their own LLM API keys rather than bundling managed access.; Primary interface is the CLI, with no first-party IDE or web UI.; Project is maintained as a smaller community tool, so enterprise-grade support and SLAs are not provided. smol developer is a single-prompt app generator — it scaffolds a full multi-file project from a one-sentence brief. Its whole idea is one prompt to a scaffold: an open-source CLI tool that takes a natural-language brief and generates the project structure, using your own LLM key so you control the model. It's for developers who want a fast starting scaffold and are comfortable on the command line. Two limits: you bring and pay for your own LLM API keys, and the interface is CLI-only — no first-party IDE or web UI. It's a one-shot scaffolder, closer to Pythagora's generate-an-app approach than to the iterative in-editor agents.
Change log
- 2026-08-27 — First published, compiled from the catalogue entries for Codex and smol developer.