Frame the comparison first
This is not a forever winner. It is which path has less friction this week: which login you already have, whether the repo may leave the building, and whether you want a TUI or an editor.
Both sides share nearby ideas: CLI, instruction files, skills, MCP. Filenames and discovery rules can still differ.
Prices, tiers, and regions change. This page quotes none of them and does not call either side a mandatory paid wall.
When Grok Build is the smoother path
You already have an xAI account or API key and want a fullscreen TUI, a plan latch, and one inspect checkup.
You need headless scripts or an ACP embed instead of another editor.
You want to read an open-source repo for implementation and issues. Open-sourced in July 2026 does not cancel account requirements.
- TUI plus plan mode is the main surface.
- inspect puts config, skills, hooks, and MCP on one list.
- Headless and ACP are first-class.
When Codex is the smoother path
You already live in a ChatGPT account, Codex CLI, or the official editor extension, and the team instruction file is written for that path.
You need to bounce between a ChatGPT workspace and the same login.
This site's Codex series already covers that path, and the team already uses it.
- Web, CLI, and extension are enough for some teams.
- Do not rewrite a working instruction file just to taste a new CLI.
Where they actually overlap
Both emphasize repo instructions, reusable skills, and MCP as an external hand.
Both expect you to read a diff instead of auto-merging.
Secrets stay out of the repo on both sides.
- Short instructions.
- Small tasks.
- One external tool at a time.
A small enough choice table
You have an xAI key and like a TUI: start with Grok Build.
You already have a ChatGPT Codex workspace: start with the Codex series.
You have both: pick one primary agent per repo so two instruction files do not fight.
- Is the main surface a TUI or an editor?
- Which account is already provisioned?
- Which headless command will CI run?
ACP versus “install another editor”
Grok Build treats ACP as the embed path. If your editor claims support, check official compatibility notes.
An embed does not magically sync ~/.grok into another product.
- Confirm the host actually speaks ACP.
- inspect after you embed.
How teams avoid a religion war
Write the primary path, the bans, and where keys live. Individuals may play on the other path; review follows the primary.
Do not force a one-week migration for everyone.
- One primary instruction file.
- CI pins one headless command.
- Personal experiments stay out of production repos.
Comparison mistakes
Scoring feature lists line by line without asking where you read the diff.
Assuming one AGENTS.md is loaded by identical rules on both sides.
- Two primary agents because of a trend.
- Writing price rumors as facts.
- Dropping bans during a migration.
You should be able to decide
Name this week's primary path and what the other path is allowed to do.
- Write down the main surface.
- Write down the account source.
- Decide the CI command.
- Keep one primary instruction copy.
Next: the troubleshooting handbook
Login, PATH, and stuck MCP look similar on both sides. The next chapter is written for Grok Build.
If you stay on Codex, open this site's Codex troubleshooting chapter.