Open Coding Agents are a family of fully open, high-performance AI coding models and an associated training method released by the Allen Institute for AI that make building, customizing, and training coding agents on any repository remarkably accessible, affordable, and transparent; the platform includes models, code, training recipes, and tools that can be launched with minimal setup so users can tailor agents to their own codebases and engineering conventions for tasks like code generation, code review, debugging, maintenance, and code explanation. These agents break from the traditional closed, expensive systems by offering an open pipeline from models to training data and enabling fine-tuning on internal code to teach agents about organization-specific APIs, patterns, and workflows; the first release, SERA (Soft-verified Efficient Repository Agents), achieves state-of-the-art performance on coding benchmarks at a fraction of the typical compute cost.