OpenCode is the open-source (MIT), provider-neutral coding agent from Anomaly: a TUI, desktop app, IDE extension, and web view built off one codebase, running against any provider’s API keys. Facts below verified as of 2026-09-12.
OpenCode is what a harness should cost in tokens, roughly a fifth of Claude Code’s measured baseline, and its 2026 security and legal history is a working lesson in why agent clients need audits too.
What it is #
The opencode TUI ships build and plan agents (Tab to switch), a general subagent, /init generating an AGENTS.md, /undo and /redo of agent changes, and shareable conversation links.
One codebase also produces a desktop app, a VS Code extension, a web view, an SDK, a server, and opencode acp, which hosts the agent inside ACP-speaking editors (Zed, JetBrains, Neovim) unchanged.
Providers are configured by API key; OpenCode Zen is the team’s curated, tested model gateway.
Status #
Very active.
The repository moved from sst to anomalyco/opencode and shows about 207k stars and 27.1k forks under MIT as of 2026-09-12.
It originated in the 2025 opencode-ai/Charm split that also produced Crush.
OpenCode is the continuation that kept the name, the domain, and the community.
Strengths #
- The leanest measured harness of the majors: about 7k baseline tokens versus about 33k for Claude Code, byte-stable cache prefixes, and about 3.7x cheaper on a matched pass/fail benchmark (
July 2026 proxy study).
- Truly provider-neutral, reading both AGENTS.md and CLAUDE.md.
- ACP support makes your editor choice irrelevant while keeping one harness.
- Undo/redo and share are small features that match how people actually work.
Cautions #
CVE-2026-22812: before v1.0.216 any website could execute code on your machine via the auto-started server; before v1.1.10 the server started silently; since v1.1.10 the server is off by default but still unauthenticated when enabled, with some vectors unfixed at disclosure.
- Pin your version and read the config.
- In March 2026
Anthropic legal requests removed the Claude Pro/Max OAuth login and Anthropic-branded defaults, so your Claude subscription will not drive OpenCode; use API keys or Zen.
- Fast-moving config surface; the docs carry ‘versions older than 0.1.x’ style of breaking-change warnings.
- Windows works best under WSL.
Pricing #
The software is free and MIT. You pay providers directly for tokens, or route through OpenCode Zen with its own billing. There is no bundled subscription usage, which is the point.
Compared to #
- Claude Code: the platform-in-a-subscription; costs more per token by design.
- Crush: same ancestor, Go and FSL-licensed, prettier; pick OpenCode for MIT and the larger community.
- aider: also BYOK, but pair-programming style rather than an autonomous loop.
Bottom line #
Recommended as the default for token-paying, provider-switching engineers. Not for teams that need subscription billing simplicity or cannot audit a fast-moving open codebase.
Changes #
- 2026-08-22 - Created in the Harnesses category seed, recording CVE-2026-22812 and the Anthropic legal-request OAuth removal.
- 2026-08-23 - Style pass: bolded each section’s key insight, hyperlinked in-body sources, and clarified referents.
See also #
- Agentic Coding Tools Landscape - the vendor-neutral slot in the harness layer
- The Shifting Bottleneck - why lean harnesses matter as generation gets cheaper
- Managing Many Concurrent LLM Agent Sessions - what running several OpenCode sessions looks like
- Claude Code - the measured token-overhead comparison
References #
https://opencode.ai/docs/ - features, install, providers, Zen