Data Flow Diagram Template

What this template is for

A data flow diagram (DFD) shows how data moves through a system: where it comes from, what processes transform it, where it is stored, and where it ends up. Unlike architecture diagrams that show components, a DFD focuses on the data itself — making it the go-to tool for understanding system behavior, documenting requirements, and finding where data can leak or get corrupted. Use this template for system analysis, requirements documentation, security reviews, and onboarding engineers to an existing system.

When to use this template

• Document how user data flows through a web application from input to storage to output.
• Analyze a business process to find where data is duplicated, lost, or manually re-entered.
• Prepare for a security or compliance audit by mapping where sensitive data is stored and transmitted.
• Communicate system behavior to stakeholders who do not read technical architecture diagrams.
• Onboard a new engineer by showing them how data moves through the existing system.
• Identify integration points between two systems before building a data pipeline.

How to use it

1. 1Identify all external entities — people, systems, or organizations that send or receive data.
2. 2List every process that transforms data within the system.
3. 3Identify all data stores where data is persisted between processes.
4. 4Draw data flows as arrows between entities, processes, and stores, and label each arrow with the data it carries.
5. 5Check that every process has at least one input and one output flow.
6. 6Review with the team to confirm the diagram matches how the system actually behaves.

Quick example