Agentless is an open-source automated software development framework developed by OpenAutoCoder. Unlike complex multi-agent architectures that rely on autonomous exploration and tool-calling loops, Agentless adopts a structured, deterministic pipeline approach to solving software engineering tasks and benchmark problems like SWE-bench. The system operates via modular command-line scripts across discrete phases. It first performs hierarchical localization to identify relevant files, classes, and code lines using repo structure analyzers and search tools. It then prompts supported frontier foundation models (such as OpenAI GPT-4o and Anthropic Claude) to generate candidate patches for the localized code regions. Finally, it validates, filters, and reranks candidate patches using syntax verification and test-suite validation. What sets Agentless apart is its intentional rejection of complex agentic scaffolding. By avoiding open-ended autonomous decision loops, tool hallucination, and runaway token expansion, it achieves high benchmark resolution rates at a fraction of the token cost and execution overhead seen in traditional agentic harnesses. Agentless is open-source software available under an open license on GitHub. Users supply their own LLM API keys, paying standard provider API rates per token consumed.
Tags: cli, code assistant, codebase, coding agent, developer tools, OpenSource