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CLI Proxy API alternatives (2026)

CLI Proxy API: MIT CLI→API bridge when you need OpenAI-shaped local access to coding-CLI seats — only if you accept the vendor ToS risk.

Its Catch: Vs Antigravity CLI / Gemini CLI / Codex themselves: this is a proxy/aggregator in front of those CLIs, not a new coding agent.

Below: 8 free or free-tier tools from the same category (coding agents), free and open source first, then the closest match by shared tags. Each keeps its own Catch.

  1. 1.PiMIT agent harness with coding CLI, unified LLM API, and TUI

    Free / OSS · OSS/MIT · 116k GitHub stars

    VerdictMIT coding-agent harness. Strong default when you want an OSS CLI + unified providers; sandbox it yourself before production credentials.

    CatchVs Prime Agent, OpenCode, OpenHands, and Claude Code: Pi is the Earendil coding-agent harness + CLI stack, not PrimeIntellect's RLM REPL, a general terminal wrapper, a full autonomous developer platform, or Anthropic's product CLI. Pi does not ship a built-in permission system for filesystem/process/network/credentials — it runs with the launching user's privileges; containerize (Docker/OpenShell/Gondolin patterns in-repo) before giving it secrets. New issues/PRs from new contributors are auto-closed by default pending maintainer review.

  2. 2.AiderAI pair programming in your terminal with any model

    Free / OSS · Apache-2.0 · 49.6k GitHub stars

    VerdictThe open-source terminal coding assistant for API-key purists.

    CatchYou are paying per-token at API rates—can exceed subscription costs on heavy use. No managed infrastructure; you are the ops team. Less polished than commercial alternatives.

  3. 3.OpenAI Codex CLIApache-2.0 OpenAI agent: CLI, IDE, app and cloud

    Free / OSS · Freemium · 130k GitHub stars

    VerdictOpenAI’s answer to terminal agents — open CLI, paid models; budget the plan or the API.

    CatchThe CLI is open source, but the models are not free: you pay through ChatGPT plan quotas or API spend. Codex Web runs on OpenAI’s cloud, not on your machine. The install.sh, brew and npm routes are supply-chain choices, so pin a release binary when that matters. Vs Claude Code or OpenCode: this is OpenAI’s first-party agent, tied to ChatGPT plans or OpenAI API keys.

  4. 4.Gemini CLIGoogle open-source terminal agent powered by Gemini

    Free / OSS · Apache-2.0 · 107k GitHub stars

    VerdictGoogle terminal agent. OSS CLI remains, but consumer quota was cut 2026-06-18; Antigravity (agy) is the consumer path. Gemini-bound by design.

    CatchGemini-bound lock-in—not model-agnostic like Goose or Crush. Consumer access (free/Pro/Ultra Google login) ended 2026-06-18; enterprise and API keys still work. Don't build on the old Google-login quota path. The OSS CLI remains. Antigravity CLI is the successor, not a 1:1 swap. Preview/nightly channels move fast; pin stable for production workflows. Enterprise path pushes you toward Vertex AI and Google Cloud project setup.

  5. 5.OpenCodeMIT OSS coding agent: CLI, TUI, desktop; BYOK/local

    Free / OSS · OSS/MIT · 217k GitHub stars

    VerdictMIT BYOK agent across CLI/desktop/IDE. The real catches are on /log: date stamp and compaction.

    CatchTwo catches worth reading on /log: “The date stamp is a trigger channel” (auto today’s-date × open-weight LoRA as a time-release fuse) and “Compaction ate the denial” (long sessions prune hard vetoes; compaction is untrusted rewrite). Re-read those two notes before you treat OpenCode as set-and-forget.

  6. 6.Kilo CodeMIT OSS IDE+CLI agent; active Cline/Roo line + MCP marketplace

    Free / OSS · OSS/MIT · 27.7k GitHub stars

    VerdictMIT IDE+CLI agent with MCP marketplace. Roo’s active heir, not a second OpenCode.

    CatchPitch IDE+platform, not “another OpenCode.” Gateway/account is convenience; BYOK stays. Marketplace and modes are the differentiator vs plain CLI harnesses. Enterprise governance rides Anaconda — evaluate if that middle layer matters for your org.

  7. 7.Open Code ReviewApache-2.0 hybrid deterministic+LLM review agent (MCP/plugins)

    Free / OSS · Apache-2.0 · 47.6k GitHub stars

    VerdictApache-2.0 hybrid review agent. Deterministic+LLM vs Semgrep/Gitleaks and vs general coding agents; BYO LLM.

    CatchVs Semgrep/Gitleaks (deterministic SAST/secrets): OCR adds an LLM agent layer for context-heavy review, not a drop-in replacement for static rules alone. Vs Claude Code/SWE-agent/OpenHands (general coding agents): OCR is a purpose-built review harness, not a full autonomous coder. BYO LLM cost — you bring the model endpoint and pay the provider; the OSS CLI itself is free.

  8. 8.gawkbotSource-available always-on bots that build microapps — local Grok Bot alternative

    Free / OSS · Open-Core · 1.5k GitHub stars

    VerdictSource-available local Grok Bot. Approval-gated personal bots; check SUL before you ship it as a product.

    CatchSustainable Use License — source-available, not OSI open-source; read the license before commercial redistribution. Vs OneCLI / AgentBox / Dexto: gawkbot is personal always-on bots + microapps, not a team credential gateway or Elastic-licensed harness. You still bring a signed-in coding agent CLI and model spend. Per-bot VM computers are still on the roadmap per README.

FAQ

What are the best free alternatives to CLI Proxy API?
Pi, Aider, OpenAI Codex CLI, Gemini CLI, OpenCode. All are reviewed on Stack Gems in the same category (coding agents); 8 free or open source.
What is the catch with CLI Proxy API?
Vs Antigravity CLI / Gemini CLI / Codex themselves: this is a proxy/aggregator in front of those CLIs, not a new coding agent.
Is there an open-source alternative to CLI Proxy API?
Yes: Pi (OSS/MIT), Aider (Apache-2.0), OpenAI Codex CLI (Freemium), Gemini CLI (Apache-2.0).

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