EONYX vs Claude Code: an honest comparison

EONYX and Claude Code are both terminal AI agents for working with code, and their workflow is similar: MCP, skills, hooks, subagents, plan mode, sessions. The difference is in the architecture and the freedom. Claude Code is tied to the cloud and to Anthropic models; EONYX is not. Here is what that gives you in practice.

1 How EONYX is different

Five practical differences — all of them follow from a single decision: not to be tied to a cloud or a vendor.

1.1 Model freedom

Claude Code only works with Claude models (Anthropic). EONYX connects directly to any OpenAI-compatible API and is not tied to a single vendor:

• OpenAI, OpenRouter, DeepSeek, Moonshot and other cloud providers;
• local model servers — Ollama, llama.cpp, LM Studio.

A model is just an entry in eonyx.json. You can keep a cheap fast model and a powerful expensive one side by side, switch on the fly (Ctrl+N), and run the same project on different providers.

A new provider is a few lines of config, not a change of tool:

"providers": {
  "openrouter": {"type": "openai", "base_url": "https://openrouter.ai/api/v1", "api_key": "$OPENROUTER_API_KEY"}
},
"models": [
  {"id": "qwen/qwen3-coder", "provider": "openrouter", "context_window": 262144}
]

Save the config, restart EONYX — and the new model is already in the Ctrl+N list: the same agent, the same skills and hooks. Ctrl+N switches between models that are already in the config; to pick up one you have just added, the TUI has to be restarted.

1.2 Local and offline

Since Ollama / llama.cpp / LM Studio are supported, EONYX can run entirely on a local model — with no internet and without sending your code to someone else’s cloud. Claude Code cannot do that: it always goes to the Anthropic API.

This matters when:

• the code must not leave the perimeter (NDA, closed network, regulation);
• there is no stable internet connection;
• you need zero leak risk — the data does not leave the machine.

Where your code goes in each case.

EONYX: your choice

sequenceDiagram
    participant U as Your code
    participant P as EONYX Terminal
    participant L as Local model
    participant C as Cloud API
    U->>P: sources, configs, secrets
    alt by default
        P->>L: processed in place
        L-->>P: response
        Note over P,L: data does not leave the machine
    else only if you choose so
        P->>C: goes to the cloud
        C-->>P: response
    end
    P-->>U: result

Claude Code: always the cloud

sequenceDiagram
    participant U as Your code
    participant CC as Claude Code
    participant A as api.anthropic.com
    U->>CC: sources, configs, secrets
    CC->>A: always goes to the cloud
    A-->>CC: response
    CC-->>U: result
    Note over CC,A: no choice

1.3 A single binary

• Installation
  • EONYX — a single static binary (Go)
  • Claude Code — npm (Node.js 18+) or an installer
• Authorization
  • EONYX — the provider’s API key, for local models — no key at all
  • Claude Code — OAuth (Claude Pro/Max) or ANTHROPIC_API_KEY
• Runtime
  • EONYX — nothing extra, a single process
  • Claude Code — Node.js

EONYX is one process with no external services, no telemetry and no OAuth. Download the binary, set a key (or point it at a local model) — and you are working. Nothing to log into, nothing that “phones home”.

From zero to the first prompt

# EONYX
# 1. download the binary from the Releases page and put it in PATH
export DEEPSEEK_API_KEY=sk-...   # 2. a key — or a local model with no key
eonyx                             # 3. done, the TUI is open

# Claude Code
# 1. install Node.js 18+
npm install -g @anthropic-ai/claude-code   # 2. install the package
claude                                      # 3. OAuth login in the browser…
# 4. …a Pro/Max subscription or ANTHROPIC_API_KEY
# 5. only now — the first prompt

Bottom line: 3 steps against 5, and not one of the EONYX steps requires a browser, an account or a runtime.

1.4 Shell in the process

The bash tool in EONYX works through the built-in mvdan.cc/sh interpreter — a system bash is not needed. The same command runs identically on Linux, macOS and Windows without WSL. The working directory and environment variables are preserved between calls. A small list of dangerous commands (shutdown, reboot, mkfs…) is blocked at the policy level.

1.5 Control over cost

• Your own key or free local models. You can run DeepSeek for pennies, or a local model for free. No subscription to a particular product is required.
• Transparent costs. The TUI header shows the number of input/output tokens, cached tokens and a cost estimate in dollars right as the session goes.
• Your own limits. max_steps, context_window, retry — everything is tuned to your budget and your model.

What a month of work costs (the Claude Pro subscription is the public price; the API spend is an example and depends on the load):

2 The honest picture

What stays with you after the switch, and where Claude Code is still stronger.

2.1 What you do not lose

EONYX is not a “stripped-down clone”. The whole familiar agent toolset is there:

• MCP client (stdio and HTTP) — external services, resources and prompts;
• Agent Skills — skills in SKILL.md with progressive disclosure;
• Hooks around tools (before/after, context via EONYX_*);
• Subagents — the task tool with an isolated context;
• Sessions in JSONL with resume, fork and search;
• Permissions and plan mode (/plan) — read-only until you approve the plan;
• Auto-summarization of history when the context window fills up;
• AGENTS.md — persistent project instructions across the directory tree.

In other words, you get the same workflow, but provider-independent.

2.2 Where Claude Code is stronger

To keep the comparison honest:

• Claude models. Opus/Sonnet are top-tier models for code; at Anthropic they come out of the box and are tuned for Claude Code.
• Ecosystem and polish. An official product: desktop and IDE apps, a web version, background tasks, support.
• Zero provider setup. Log in with a subscription and everything works, no need to touch a config.

EONYX wins on other things: freedom, locality and no lock-in. If what you need is Claude models specifically and the smoothest possible official experience — Claude Code is the better fit. If you need a single local binary, any provider (including offline models) and full control over data and cost — EONYX.

3 Summary

3.1 Comparison table