A comparison of terminal agents — Claude Code, Codex, Gemini CLI (now transitioned to Antigravity CLI), OpenCode, Pi, Cursor CLI, and Kiro — covering each one's design trade-offs, plans, and billing, closing with a cross-tool subscription comparison and multi-model routing. Pricing and model names rot fast, so every post carries its verification date and defers the perishable details to official pages.
Agent CLIs are not smarter autocomplete tools -- they are AI agents that can read your codebase, execute multi-step tasks, and operate in real environments. Claude Code, Codex CLI, Gemini CLI, OpenCode, Aider, Pi, Kiro, Amp, Cursor CLI... the tools keep multiplying, but they all share a common set of design principles -- understanding these principles is how you actually get good at using them.
Claude Code is Anthropic's agentic coding tool that runs in the terminal, IDEs, Slack, GitHub, and on the web. Its core extension system has six layers: CLAUDE.md (persistent context), Skills (on-demand workflows), Hooks (deterministic automation), Subagents (isolated delegation), MCP (external tool connections), and Agent Teams (multi-agent collaboration).
Claude Code runs from $20/mo Pro to $200/mo Max 20x. Quota is a rolling five-hour window with weekly limits on top, shared across Claude on web, desktop, mobile, and the terminal. When you run out you can switch to usage credits at standard API rates rather than stopping.
Codex CLI is OpenAI's open source terminal coding agent (Rust, Apache-2.0, ~106.6k stars) with MCP, subagents, image input, code review, and Skills. The model line is now GPT-5.6 Sol / Terra / Luna, and the desktop app, CLI, and IDE extension share one config.toml.
Codex rides your ChatGPT subscription (Free / Go $8 / Plus $20 / Pro 5x $100 / Pro 20x $200), and since 2026/4/2 billing is token-based credits. The model line is GPT-5.6 Sol / Terra / Luna; GPT-5.4 and 5.4 mini retire from ChatGPT-signed-in Codex on 2026/8/31.
Gemini CLI is Google's open source terminal AI agent (Apache 2.0, ~106.6k stars). It once offered 60 requests per minute and 1,000 per day for free, with a 1M context window. The individual tier stopped serving on 2026/6/18 and Antigravity CLI took over. The project isn't shut down — the repo is still maintained — but it now serves only Gemini Code Assist Standard/Enterprise licenses and paid API keys.
Antigravity CLI is a terminal agent Google announced at I/O on May 19, 2026. Written in Go (versus Gemini CLI's Node.js), its binary is called agy, and it shares the same agent harness as the desktop Antigravity 2.0. It is also Gemini CLI's successor — the personal-tier Gemini CLI service ends on June 18, 2026.
The paying paths on Google's side: the individual free tier and Gemini CLI access on Google AI Pro / Ultra ended 2026/6/18, leaving individuals with Antigravity CLI or their own paid API key; enterprise licenses and Google Cloud are unaffected. The zero-cost starting option now belongs to someone else.
OpenCode is an open-source AI coding agent written in TypeScript (MIT, repo at anomalyco/opencode) with a built-in TUI, 75+ LLM providers, LSP integration, a Vim-style editor, SQLite session management, and a desktop app. The tool is free; native free models and paid or local providers are separate choices.
OpenCode is a free, open-source TypeScript CLI agent (MIT). It supports 75+ model providers including local Ollama, can connect external providers and supported subscription plans, and lets you switch models mid-session. There is also a desktop app, built-in free models, and an optional Console service.
Pi is a minimalist coding agent by Mario Zechner (TypeScript, MIT, ~93K stars) with just 4 core tools and a very short system prompt — everything else you add yourself via Extensions, Skills, and Prompt Templates. It deliberately omits MCP, sub-agents, plan mode, and permission popups. The repo is now earendil-works/pi and the npm scope is @earendil-works.
Cursor CLI brings the IDE agent to the terminal with an interactive TUI and headless mode, Plan/Ask/Agent modes, Cloud Handoff, and CI/CD integration. Billing now runs on two separate usage pools: Cursor's own models (Grok 4.6/4.5, Composer 2.5) and third-party models (Pro includes $20, Pro+ $70, Ultra $400).
Kiro has five tiers: Free 50 credits, Pro $20/1,000, Pro+ $40/2,000, Pro Max $100/5,000, and Power $200/10,000, with add-on credits at $0.04. Auto mode mixes models to cut cost (the same task costs 1.3x credits via Sonnet), and the spec-driven flow turns vibe coding into traceable, structured development.
Aider is a terminal AI pair programmer dating back to 2023 (Python, Apache-2.0, ~48.3k stars), designed against the grain of today's autonomous agents: you control context by hand with /add, every edit becomes its own atomic git commit, and architect/editor mode splits planning from editing across two models. But note the maintenance cadence: the latest PyPI release is 0.86.2 from 2026-02, the last commit was 2026-05, and the site still recommends Claude 3.7 Sonnet and o1.
Copilot CLI went GA on 2026-02-25 and is included in every Copilot plan, Free included. Its differentiator isn't the agent — it's the GitHub integration: a built-in GitHub MCP server that works on issues and PRs, org policies inherited automatically, and an `&` prefix that hands work to the cloud coding agent. Billing runs on GitHub AI Credits (1 credit = $0.01): Pro $10/mo includes $15, Pro+ $39 includes $70, Max $100 includes $200.
omp is a fork of Pi, but it is not just a plugin layer stacked on top: it adds roughly 80,000 lines of Rust, pulling grep, shell, AST, and PTY in-process. Built-in tools go from Pi's 7 to 31, plus 14 LSP ops, 28 DAP ops, and 60+ providers. One codebase, two opposite bets.
Amp spun out of Sourcegraph in December 2025 as Amp Frontier Corporation, and its npm package moved from @sourcegraph/amp to @ampcode/cli. Its defining trait is deletion: the editor extension, Amp Tab, TODO lists, Fork, custom commands, and public threads have all been removed. Monthly subscriptions only arrived on 2026-07-18 (Megawatt $20, Gigawatt $200); before that it was pay-as-you-go only. The current focus is orbs — remote machines that keep working after you close your laptop.
Claw Code is a from-scratch Rust rewrite of the Claude Code CLI, featuring 48K lines of code, 40 tools, and MIT licensing. Most remarkably, the entire project was built by multiple AI agents collaborating over just 5 days, surpassing 170K GitHub stars within a week of launch.
goose is an open-source AI Agent maintained by the Linux Foundation's AAIF, supporting 15+ LLM providers and 70+ MCP extensions, built with Rust as a Desktop App + CLI + API. It positions itself as a vendor-neutral, self-hostable alternative to Claude Code.
Warp evolved from a Rust-powered modern terminal into an AI Agent-integrated development environment (ADE), open-sourced under AGPL in April 2026, with over 700,000 developer users.
A comparison of six agent CLI subscriptions (Claude Code, Cursor CLI, Codex, Kiro, Antigravity/Gemini CLI, OpenCode) plus the multi-model routing pattern — cheap models for simple work, strong models for hard work. Nearly every one of these changed its billing in the first half of 2026; this version was re-verified on 8/18.
With multi-model routing, 70% of simple tasks are directed to cheap models, and only 10-15% of complex tasks use flagship models — saving 40-85% on inference costs in practice. This article covers the architecture and implementation of five major open-source tools.
OMP 2 is no longer a Pi fork. The entire codebase has been rewritten from scratch in Rust, with ~41 crates covering a custom bash engine, GPU-accelerated GUI, embedded CPython 3.14t, gRPC transport, and Kokoro-82M TTS. Currently in pre-release with no stable version yet.
Pi v0.84.0 (2026-08-06) promotes the AgentHarness v2 API to stable. Lane-based v4 Session model makes operations durable and interruptible. CBOR replaces JSON, Unix sockets replace HTTP. Earendil Inc. (Armin Ronacher's PBC) behind it has secured initial funding. 95.4K stars, still MIT, still minimal.
Opencode 2 is a major rewrite led by Anomaly (Dax Raad). Runtime migrated from Bun to Node.js (memory issues), desktop from Tauri to Electron (WebKit perf and Node integration), v1 API intentionally incompatible. New: multi-tab parallel sessions, persistent backend service, HTTP API and CLI integration. The current CLI package is @opencode/cli and the command remains opencode. Built-in free models are available alongside paid Console and Go options.
DeepSeek Harness (dsh) is DeepSeek's official open-source coding agent framework, released as a v0.1 developer preview on 2026-08-13, accumulating 184,000+ stars in 9 days. Its core is the Cordis plugin kernel — model adapters, tools, agent loop, and UI are all swappable plugins. Four runtime modes, with the ability to use Claude Code and Codex as sub-agents. Web UI first, no native CLI.
At Google I/O 2026, Antigravity CLI (agy) replaced Apache 2.0 Gemini CLI with a closed-source Go binary. Technical upgrades — multi-agent orchestration, native sandbox, millisecond startup — but free tier cut 98%, open-to-closed source, 28-day transition window. Community reaction was sharp.
In August 2026, Meta Superintelligence Labs released Muse Code beta. Closed-source static binary, Muse Spark 1.2 model, parallel persistent sub-agents with worktree isolation. The biggest controversy is pricing: Standard at $1.25/$4.25 per M tokens, or Contributor at $0.10/$0.20 — 20x cheaper, but your code enters Meta's training pipeline.
Grok Build is xAI's Rust coding agent — 845K LOC, 8 parallel sub-agents, Arena Mode. May 2026 beta, July open-sourced (Apache 2.0) — but the direct trigger for open-sourcing was a privacy incident: it silently uploaded entire repos (including SSH keys, .env files) to Google Cloud Storage at a 27,800x traffic ratio. The exfiltration code remains in the binary, disabled only by a server-side flag.
In August 2026, it's not just five frameworks moving. Beyond OMP 2, Pi v2, Opencode 2, dsh, and Claude Code, three model makers — Google (Antigravity CLI), Meta (Muse Code), and xAI (Grok Build) — are building coding agents directly. Add Amp, Cline 2.0, and the Codex CLI Rust rewrite, and eight-plus frameworks are undergoing architecture-level changes simultaneously. Factor in 110+ total CLI tools, and H2 2026 is a divergence period for harness methodology. This article analyzes four architectural approaches, one shared direction, and one emerging trust crisis.