ChainForge vs Vellum

ChainForge is an open-source visual programming environment for prompt engineering, LLM evaluation, and experimentation. It can query multiple language models at once and compare results across prompts, models, and model settings. Responses can be scored with code-based or LLM-based evaluators, then plotted for review. Chat Turn nodes support continuing multiple conversations, templating chat messages, and handing a conversation from one model to another. The tool imports JSONL, XLSX, and CSV files and exports inspected response data as XLSX. Listed providers include OpenAI, Anthropic, Google Gemini and PaLM, Hugging Face, Azure OpenAI, Amazon Bedrock, and Ollama. A local installation can add custom providers written as Python completion functions. The web version has a limited feature set; local use supports API keys from environment variables, Python evaluation code, and locally hosted Alpaca or Llama models via Dalai. Web users must set API keys each time they load the app, and the documentation says keys are not stored. ChainForge is available on the web or self-hosted, is free and open source, and is described as an open beta in active development.

Vellum is a personal AI assistant that can read files, manage calendars, send email, run code, and control a computer. It saves preferences and context in its workspace for later conversations, and users can create, install, and manage skills. Listed OAuth services include Discord, GitHub, Google services, HubSpot, Linear, Twitter (X), Asana, Notion, Microsoft Outlook, and Todoist. Vellum says OAuth tokens stay in a credential vault rather than being exposed to the language model. Sensitive actions prompt for approval, and users can set trust rules for standing permissions. By default, conversation context is sent to Anthropic to generate responses; OpenAI, Google, OpenRouter, Fireworks, and local Ollama are listed alternatives. An internet connection is required. Vellum Cloud runs assistants in isolated environments with private storage and 24/7 availability. The Free plan includes first tasks and pay-as-you-go credits. Mighty costs $30 a month, Super $100 a month, and Ultra $200 a month. There is no shipped Linux desktop client, but Linux users can use the web app, Chrome extension, or self-host the runtime.