Claude System Prompt Builder

Build a structured system prompt for Claude in seconds. Set the role, tone, task, output format, and constraints — get a ready-to-paste prompt for Claude API or Claude.ai. No AI, no sign-in.

Role / Persona

Used in: "You are ___"

Task focus

Tone

Output format

Response language

Background context (optional)

Constraints (one per line, optional)

Generated system prompt

Fill in the fields to generate your system prompt...

Paste this into the System prompt field in Claude.ai or as the system parameter in the Claude API.

What is a Claude system prompt?

A system prompt is an instruction set you provide to Claude before the conversation starts. It defines the AI's role, behavior, tone, and constraints. When using the Claude API, it is passed as the system parameter. In Claude.ai, you can set it in the "System prompt" field of a Project.

How to use this tool

Fill in the role your Claude assistant should play.
Describe the task it should help with.
Set tone, output format, and any constraints.
Copy the generated prompt and paste it into Claude API or Claude.ai.