Melvin Vivas's open-source AI tools, built with Codex

Melvin Vivas · X post · 2026-09-14 · Open on X

Topics: AI Dev Tools & Productivity, AI Agents, Tool Use & MCP, Evaluation (Evals) & Testing · Level: intermediate

Summary

Melvin Vivas lists eight open-source projects he builds and maintains mostly with OpenAI Codex. They cover multi-agent orchestration in Codex, a single API for AI tasks on local and cloud models, local evals, an AI coworker app, a JSONL dataset viewer for fine-tuning data, a Markdown editor with local AI editing, and reusable agent skills. Together they give learners working code to study and use across agents, evals, LLMOps and fine-tuning.

Key points

codex-astra-luna-orchestrator: uses Astra (or Sol) as the root orchestrator and Luna models as subagents inside Codex.
ai-backends: an API server for common AI tasks. It runs locally with Ollama or LM Studio, or in the cloud through OpenRouter, OpenAI or Anthropic.
local-evals: an eval app that runs on your machine against local models or any OpenAI-compatible API.
coworker: an open-source AI coworker with skills, tools, and support for local and cloud models.
aibackends: a Python library for running common AI tasks locally on your GPU.
jsonl-viewer: lets you view and edit JSONL datasets for fine-tuning and training.
markdown-editor: a lightweight Markdown editor with local AI editing; skillsbento: free reusable skills for AI agents.
He uses Codex heavily to maintain these projects and asks OpenAI to support open-source work with more usage.

Resources mentioned

donvito/codex-astra-luna-orchestrator · repo · github.com · free
The creator's Codex skill for an orchestrator-plus-subagents setup (Astra orchestrator, Luna subagents), configured through config.toml.
Also in: Codex Orchestrator Pattern: Astra/Sol Orchestrator with Luna Subagents (Melvin Vivas on X · notes), Open-source Codex skill: Astra/Sol orchestrator with Luna subagents (Melvin Vivas on X · notes), Cost-Efficient Codex Subagents: Astra/Sol Orchestrator + Luna Workers (Melvin Vivas on X · notes), Codex Orchestrator v0.2.1: GPT-6 Sol orchestrator with Luna subagents (Melvin Vivas on X · notes) and 27 more
AIBackends · repo · aibackends.com · free
Open-source API server runtime for common AI use cases that supports many models and providers (Ollama, LM Studio, OpenRouter, OpenAI, Anthropic).
Also in: Building a production website with Opus 5.5 and TanStack (Melvin Vivas on X · notes), CamelFlow: open-source visual viewer for Apache Camel routes (Melvin Vivas on X · notes), AI Backends: A Production AI Workflow Engineering Site (Link Share) (Melvin Vivas on X · notes), Demo: Claude Opus 5.5 Generating a Motion-Graphics Video for AIBackends (Melvin Vivas on X · notes) and 16 more
donvito/local-evals · repo · github.com · free
Eval app that runs locally and tests local models or any OpenAI-compatible API on JSON extraction and tool calling.
Also in: local-evals: A Local LLM Eval App Built by Codex Subagents (Melvin Vivas on X · notes), Measure Your Own Codex Token Burn: Orchestrator+Subagents vs Single Agent (Melvin Vivas on X · notes), Local Evals: Open-Source App for Evaluating Local or OpenAI-Compatible Models (Melvin Vivas on X · notes)
Coworker (donvito/coworker) · repo · github.com · free
The creator's local-first desktop app where you pick an AI coworker and have it produce work such as invoices as finished PDFs.
Also in: Claude Opus 5.5 for Video Making: Creator's Showcase Thread (Coworker) (Melvin Vivas on X · notes), Coworker: free open-source desktop AI coworker app (Melvin Vivas on X · notes), Coworker: Open-Source Desktop App for AI Agents (Melvin Vivas on X · notes), Using Devin AI to Test the Coworker Desktop App on Windows (Melvin Vivas on X · notes) and 38 more
donvito/jsonl-viewer · repo · github.com · free
Open-source tool for viewing and editing .jsonl files (fine-tuning datasets) and agent traces from Codex, Claude Code, Pi and Hermes.
Also in: jsonl-viewer: Live Traces for Codex Orchestrator and Subagents (Melvin Vivas on X · notes), See live Codex traces with the jsonl-viewer tool (Melvin Vivas on X · notes), Analyzing Codex Traces with jsonl-viewer (Melvin Vivas on X · notes), jsonl-viewer: Inspect Coding Agent Traces (Codex, Claude Code, Pi, Hermes) (Melvin Vivas on X · notes) and 12 more
donvito/markdown-editor · repo · github.com · free
A lightweight markdown editor with AI editing that works with Ollama and LM Studio.
Also in: Markdown Editor v1.4.2: Local AI Editing with Ollama/LM Studio (Melvin Vivas on X · notes), Open-source AI Markdown Editor v1.4.1 for local LLMs (Melvin Vivas on X · notes), Open-Source Markdown Editor with Local and API AI Editing (Melvin Vivas on X · notes)
skillsbento · website · skillsbento.com · free
Melvin Vivas's GitHub plugin and skills marketplace for Codex and Claude Code, which includes the devils-advocate plugin.
Also in: SkillsBento: Free Plugin Marketplace for Codex and Claude Code (Melvin Vivas on X · notes), Countering AI Sycophancy with a Devil's Advocate Plugin for Codex & Claude (Melvin Vivas on X · notes), Agent Skill to Analyze Your X (Twitter) Analytics Export (Melvin Vivas on X · notes), skillsbento: Free Open-Source Agent Skills for Claude (Melvin Vivas on X · notes) and 2 more
OpenAI Codex · tool · openai.com · paid
OpenAI's coding agent. In the diagram it writes code, fixes review findings and drives the build loop. The creator also used it to make this video.
Also in: An agent bot that installs and drives Codex on its own (Melvin Vivas on X · notes), Asking a Coder bot to install Codex (Melvin Vivas on X · notes), Sign in with ChatGPT: Setting Usage Limits for Each App (Melvin Vivas on X · notes), Codex Cloud Environments Must Be Saved & Published Before Use (Melvin Vivas on X · notes) and 240 more

Try this

Explore the repos and try local-evals or ai-backends with local models, e.g. via Ollama or LM Studio.
Set up an orchestrator with subagents in Codex, modeled on codex-astra-luna-orchestrator.
Build an eval app that runs locally against OpenAI-compatible APIs.
Build a tool for viewing and editing JSONL fine-tuning datasets.