Building a Zero-Cost AI Coding Environment

The Core Architecture

The setup relies on integrating three distinct services into the OpenCode terminal agent to create a unified, cost-free coding environment. By leveraging official provider integrations within OpenCode, users can switch between frontier-level models without manual configuration files or base URL overrides.

Model Sourcing and Integration

• NVIDIA NIM: Access the NVIDIA NIM catalog to utilize free preview endpoints. Filtering by "preview NIM" reveals approximately 77 models, including Nemotron 3 Ultra, MiniMax M3, and Step 3.7 Flash, which are suitable for development and testing.
• ZenMux: Use ZenMux to access Moonshot AI's Kimi K3 model. The model is currently listed as moonshotai/kimi-k3-free and provides a 2.8 trillion parameter model with a 1 million token context window at no cost.
• OpenCode Integration: Connect both NVIDIA and ZenMux directly through the OpenCode provider settings using your respective API keys. This enables a single model picker interface to manage all available endpoints.

Operational Workflow

• Primary Agent: Use Kimi K3 for long-horizon coding tasks. The model performs best when prompted with the final goal and verification criteria rather than step-by-step instructions.
• Speed Tasks: Switch to Step 3.7 Flash for quick refactors, documentation updates, or simple bug fixes where low latency is prioritized.
• Multimodal Requirements: Utilize MiniMax M3 for tasks involving screenshots or design-heavy front-end work.
• Reasoning Backup: Deploy Nemotron 3 Ultra for complex planning or when a second reasoning perspective is required for a specific task.

Usage Caveats

These free tiers are intended for development, testing, and personal projects rather than production services. NVIDIA preview endpoints are subject to rate limits and potential deprecation, and the free access to Kimi K3 via ZenMux is a time-limited promotional offer.