Prompt Octopus

Prompt Octopus is a developer tool. A VS Code extension for prompt engineering that runs 40+ models from OpenAI, Anthropic, DeepSeek, Mistral, Grok and others against your prompt and shows the answers side by side. Bring your own API keys for unlimited local use, or pay $10/mo for hosted servers.

Prompt Octopus is a VS Code extension that turns prompt engineering into a side by side comparison exercise. Instead of pasting a prompt into one model, noting the answer, then repeating the process elsewhere, you highlight the prompt text inside your editor, pick the models you want to test, and read the responses next to each other. It covers OpenAI, Anthropic, DeepSeek, Mistral, Grok and dozens of other providers, with more than 40 models available in total. The tool is aimed at engineers who already tune prompts as part of their development work: people writing system messages, evaluation harnesses, or model selection tests who want quick evidence of which model handles a given task better. Because it runs inside the codebase, the prompt stays where it is versioned, and the comparison happens without leaving the editor or copying text into a browser tab. Prompt and model preferences can be saved, so recurring comparison setups do not need to be rebuilt each session. Billing works through a bring your own key model. You enter API keys for the providers you want, and those keys are stored locally and never seen by the company's servers, which means unlimited usage at the provider's own rates. Alternatively, Prompt Octopus offers hosted access for $10 per month, using its own servers instead of your keys. New users get 10 comparisons free before either path is required, so the workflow can be evaluated without payment or key setup. Prompt Octopus fits the narrow gap between general chat interfaces and full evaluation frameworks. It is lighter than wiring up an eval harness and more focused than comparing models across browser tabs, though it is not a substitute for automated testing at scale. Teams that mainly need prompt storage and sharing will find dedicated prompt management libraries a better home; people whose priority is fast model selection during development will find the extension well matched to that task.