Short answerDevelopers can rebuild on a model API with tool calling and retrieval, expose tools through MCP, use an SDK for the chat interface, or start from an open-source builder like Dify or Langflow.
- Model APIs: OpenAI API, Anthropic API; compare costs.
- Retrieval: OpenAI file search, Cloudflare AI Search, or your own (vector stores).
- Tools: MCP, schema mapping, structured outputs.
- Interface and app: architecture overview (OpenAI function calling and the Vercel AI SDK are official starting points).
- Open-source builders: Dify, Langflow, compared.
- Operations: keys and limits, rate limits, protection.
Feature equivalents in one place: API equivalents.
Not sure it is simple enough to do yourself?
Tell us what your GPT does, whether it uses Actions and how many files it has. We will say what will break and what a rebuild involves. The audit is free.
Request a free auditRelated guides
Sources
- OpenAI developers: Function calling
- Vercel AI SDK: Introduction
- OpenAI docs: Build an MCP server for plugins
- Langflow on GitHub
- Dify on GitHub
Pages describing other companies' products reflect their public documentation on the date shown and can go out of date.