Prompt Engine vs Vellum

Prompt Engine is a web platform for creating, editing, organizing, and optimizing prompts for ChatGPT and other AI systems. Its assisted optimizer reviews prompts and suggests improvements, while prompt testing and dynamic template variables let users preview templates with entered values. Users can assemble multi-step prompt chains, with separate content and variables at each step. A library organizes prompts using folders, subfolders, tags, search, and grid or list views. The curated template collection can be copied to a personal library and customized. The FAQ says prompts can be created for systems including OpenAI, Anthropic Claude, Google, and open-source models. Personal-library prompts are private to the account, while administrators can create public templates; users can export individual prompts or their whole library. The free-forever Hobby plan allows up to 10 prompts and includes basic optimization, 25 credits, limited features, and email support. Pro costs $4.99 a month, with a yearly option at 49 USD per year. A one-time pack of 100 optimization credits costs 4.99 USD. Support resources include documentation, video tutorials, a blog, and email support.

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.