otisworks/batch-kit

batch-kit is a command-line tool and code library that helps you send large batches of documents to Claude for processing at half the normal API cost. It is built for developers using Anthropic's Message Batches API, but it removes the manual work normally involved. Instead of hand-crafting request files, tracking batch identifiers, or writing polling logic, you use a short set of commands that resemble how git works. The workflow has four main steps: add, review, send, and fetch. You start by pointing the tool at a folder of documents and giving it a prompt template with placeholders like {content} for the file text. You can review what is staged, send it as a single batch, and later fetch the results back into a JSON file. The tool keeps a local state directory, similar to git's hidden folder, so it remembers which batch is the most recent and maps each result back to its original filename across terminal sessions. You can use it as a command-line program with npx batch or install it globally for the shorter batch command. It requires Node.js 18 or higher and an Anthropic API key set in your environment or a .env file. There is also a TypeScript library API for programmatic use, letting you add documents, submit batches, wait for completion with polling callbacks, and stream results as they arrive. State is stored locally per directory on the machine you run it from. If you send a batch from one computer, you need that same machine's state folder to use the --latest shorthand later, though you can always fetch by explicit batch ID from anywhere. The tool assumes a single user and non-concurrent usage, with atomic writes to prevent corruption if a process is interrupted. It supports text and markdown files by default, with options to filter by extension, override the model, and set token limits.