Grok Build vs Muse Code
Both are brand-new 2026 challengers to Claude Code and Codex from major AI labs, and both parallelize work across sub-agents in isolated git worktrees — but they take different approaches everywhere else. Grok Build is bundled into an existing SuperGrok or X Premium+ subscription and defaults to a plan-first approval step before editing files. Muse Code is pure usage-based with a much larger context window and crash-safe session resume for very long jobs. Grok Build had a serious July 2026 privacy incident; Muse Code's cost advantage requires opting into data-training on its discounted tier.
Grok Build
Choose if: You already pay for SuperGrok or X Premium+, want a plan-first workflow that asks for approval before editing files, and prefer a flat bundled price over metered billing.
xAI's terminal-native autonomous coding agent
Muse Code
Choose if: You need the largest context window for whole-repo work, want crash-safe resume on very long unattended jobs, and are comfortable with usage-based billing — or the discounted data-sharing tier for non-sensitive work.
Meta's terminal-based autonomous coding agent
Feature Comparison
| Feature | Grok Build | Muse Code |
|---|---|---|
| Context window | 256K tokens | 1M tokens✓ |
| Pricing model | Bundled subscription ($30–$300/mo) | Pure usage-based ($1.25/$4.25 per 1M tokens) |
| Parallel sub-agents | Up to 8, isolated worktrees | Isolated worktrees (count unspecified) |
| Workflow | Plan Mode drafts plan for approval first✓ | Executes directly |
| Session persistence | Standard | Crash-safe resume, replay-exact logging✓ |
| Platform | Terminal (CLI) | CLI only, macOS/Linux |
| Privacy/data caveats | July 2026 repo-upload incident | Contributor tier requires opting into training on your code |
| License | Source-available (Apache 2.0), no external contributions accepted✓ | Proprietary |
Pricing Comparison
Grok Build
| SuperGrok (bundled) | $30/mo |
| X Premium+ (bundled) | $40/mo |
| SuperGrok Heavy (bundled) | $300/mo |
+ No standalone Grok Build plan — access is bundled into an existing xAI/X subscription, Pay-as-you-go API pricing also available; exact current rates conflict across sources (~$1-2/1M input, $2-6/1M output tokens) — verify directly before relying on a specific figure, Open-sourced (Apache 2.0) July 2026, but xAI doesn't accept external pull requests or issues — 'source-available' rather than community-governed
Muse Code
+ No flat monthly subscription — pure usage-based (token) billing, payment method required upfront, Standard tier: $1.25/1M input tokens, $0.15/1M cached input, $4.25/1M output tokens, Contributor tier (~12-21x cheaper): $0.10/1M input, $0.002/1M cached input, $0.20/1M output — requires opting in to let Meta train on your prompts and code, Enterprise zero-data-retention available on request via Meta sales
Pricing last verified: 2026-08-12
Grok Build: Strengths & Limitations
Strengths
- +Plan Mode by default — drafts a structured plan for human approval/edit before touching any files
- +Up to 8 parallel sub-agents in isolated git worktrees for large multi-file migrations
- +Cheapest frontier-class pricing among the major terminal agents (Claude Code, Codex CLI, Grok Build)
- +Low switching cost — reuses existing conventions (AGENTS.md, MCP servers, hooks) from Claude Code and Codex
Limitations
- -Serious July 2026 privacy incident — a researcher found it silently uploading entire git repos, including secrets and commit history, to an xAI cloud bucket at ~27,800x the data a task needed; xAI says it's fixed and deleted the data, but no independent audit has confirmed that
- -Lower benchmark scores than rivals — 70.8% SWE-bench Verified vs. Claude Code's ~87.6% and Codex CLI's ~88.7%
- -Smaller context window — 256K tokens vs. Claude Code's up-to-1M-token option, a real constraint on large monorepos
- -Mixed early-beta reception — Hacker News users reported hallucinations, harness crashes, and being '6 months behind' competitors
Muse Code: Strengths & Limitations
Strengths
- +Persistent, crash-safe sessions — every model call, tool run, and edit is logged and replay-exact, enabling resume after crashes on very long jobs
- +True parallel sub-agent fan-out with isolated git worktrees — large jobs split across simultaneous agents without collisions
- +1M-token context window, co-trained model+harness specifically for tool-calling and whole-repository tasks
- +Aggressive Contributor-tier pricing — 12-21x cheaper for high-volume, non-sensitive work like tests and dependency bumps
Limitations
- -Trails Claude Code (Opus) on Meta's own published benchmarks (e.g. Terminal-Bench 2.1: 82.9% vs 86.7%) — a late entrant competing against an established leader
- -The cheap Contributor tier isn't free — it's a data-for-discount trade: you sign away rights to your prompts/code for model training, a poor fit for proprietary codebases
- -CLI-only, beta-stage, macOS/Linux only — no Windows support, no IDE integration at launch
- -Correctness requires expert review — independent testing found output 'looked correct on the surface' but needed an expert to verify it was actually finished underneath
Which One Should You Pick?
Grok Build is best for: Developers already on a SuperGrok or X Premium+ subscription who want a low-cost, plan-first CLI agent for parallelizable work — not yet a strong choice where Claude Code or Codex CLI currently lead on accuracy and trust.
Muse Code is best for: Cost-conscious developer teams with large, existing codebases who want a terminal-based autonomous agent for long-running, multi-file engineering tasks — best suited to non-sensitive or open-source work on the discounted tier.
Last updated: 2026-08-16