
Claude Code is one of the most capable agentic AI tools for software development – but it comes with a practical constraint: usage limits and spend. It's easy to run into daily or weekly quotas, and API costs can add up quickly.

Fortunately, there's a workaround.

### Ralph Loop: Running an Open-Source Coding Agent on Vast.ai

Instead of relying on API-limited services or local hardware, you can run open-source coding agents on Vast.ai for about **$1.50 per hour** – even continuously overnight! One example of this is Ralph, an agentic coding loop designed to implement software projects from a Product Requirements Document (PRD).

Ralph picks a user story, writes the code, runs tests, fixes any failures, and moves on to the next story. This process repeats until the project is complete and everything passes.

To jump straight in, follow our [Overnight Ralph Loop guide](https://docs.vast.ai/examples/ai-agents/overnight-ralph-loop) to get started. Otherwise, let's explore some more about what you can accomplish with Ralph and why.

### Why Run the Ralph Loop on Vast.ai?

There are several practical reasons to run the Ralph loop on a self-hosted model using our dedicated GPU infrastructure.

First, cost becomes more manageable. On Vast.ai, you pay for GPU time directly, at cost-effective rates that make overnight runs both predictable and affordable. Ralph is built for sustained workflows, so you can run it continuously without the usage caps of API-based tools like Claude Code.

Running Ralph on Vast.ai also gives you direct control over your development environment and supports stricter security and [compliance](https://vast.ai/compliance) needs. At the same time, you can match model size and GPU compute to the complexity of the task, ensuring your resources scale up only when the workload requires it.

### The Ralph Loop in Practice: Model & Use Cases

On Vast.ai, you can run the Ralph loop on Qwen3-Coder-Next, a large Mixture-of-Experts (MoE) model trained specifically for agentic coding tools like Claude Code, Aider, and Cline. It boasts a 256K context length and strong performance across multi-step coding tasks involving large codebases.

Once deployed, Ralph operates continuously and autonomously on real software projects, making it well suited for overnight development workflows. Common use cases include:

- Building a full CLI application
- Implementing REST APIs with authentication and validation
- Generating complete test suites for existing codebases
- Creating a web scraper with multiple site adapters, rate limiting, and data export

You simply define the requirements and allow the agent to carry out the work unattended.

### Getting Started with the Overnight Ralph Loop

With Vast.ai, a typical setup using Qwen3-Coder-Next on a 4x RTX 4090 instance costs approximately $1.50 per hour, with an overnight run often coming in **under $18** .

Our [Overnight Ralph Loop guide](https://docs.vast.ai/examples/ai-agents/overnight-ralph-loop) walks you through deploying the model, connecting the agent, and running the Ralph loop on Vast.ai. Start your first overnight run today!


Run autonomous coding agents on Vast.ai for about $1.50/hour with the Ralph Loop workflow.

Posts about: Coding

Affordable Claude Code Alternative: Run Autonomous Coding Agents on Vast.ai