Free Online DFD Maker

Draw Level 0, Level 1, and Level 2 DFDs from a short description. The AI maps external entities, processes, data stores, and data flows automatically - no manual shape work.

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Authentication-system DFD

A simplified login system as a Level-1 DFD.

Pencil sketch with a User entity square on left, an Authenticate process circle in the middle, and a Sessions data store on the right

Input

Generated data flow diagram with numbered processes, labelled data flows, and Yourdon-DeMarco notation conventions

What the AI produces

Auditors love this exact diagram — it clearly shows trust boundaries (User is outside the system), credential flow, and audit logging in a single image.

What is a DFD maker?

DFD stands for Data Flow Diagram — the classic notation for showing how data moves between external entities, processes, and data stores. Flowova's DFD maker takes a short description ("a user submits an order, the validator checks inventory, payment processor charges Stripe, the order is written to the orders database") and produces a properly leveled DFD with external entities as squares, processes as circles, data stores as open rectangles, and labeled data-flow arrows. Specify Level 0 / 1 / 2 in your prompt to control depth.

Written by Lin Park

Build a DFD in Three Steps

1

Describe the System and Level

Describe the data: external sources, processes, and stores. The DFD maker accepts the same input as the long-form Data Flow Diagram Maker.

  • Short description: entities, processes, stores, flows
  • Pick Level 0 / 1 / 2 in your prompt
  • Up to 12,000 characters per generation
2

AI Builds the DFD

The AI builds a DFD with external entities, processes (numbered), and data stores. Yourdon notation by default; Gane/Sarson on request.

  • Squares for entities, circles for processes, open rectangles for stores
  • Processes numbered (1, 1.1, 1.2…); stores labeled D1, D2 for traceability
  • Yourdon-DeMarco by default; Gane–Sarson on request
3

Refine and Export

Refine, validate level (0 vs 1), and export. DFDs are the standard format for threat modeling (STRIDE), system design, and compliance documentation.

  • Edit labels and re-route arrows inline
  • Decompose a process into a Level 2 sub-diagram
  • Free PNG; SVG and Mermaid are Pro

DFD Maker Features

Level 0 context diagram: single large process circle surrounded by three external entity squares

Level 0 Context Diagram

A single-process Level 0 (context) DFD showing the system boundary, external entities, and the major data flows in and out — useful for stakeholder kickoffs.

Level 1 DFD with four numbered process circles connected to a data store rectangle

Level 1 Decomposition

3-7 numbered sub-processes with the right data stores and flows between them — the level of DFD most teams actually deliver in system docs.

Process circle on left with magnifier and a decomposed sub-DFD with three smaller circles on right

Level 2 Detail

Decompose a specific Level 1 process into a Level 2 DFD when you need to specify behavior at the implementation level for engineering hand-off.

Two DFD circles connected by an arrow with a data label flag reading payment token

Labeled Data Flows

Every arrow carries a label that names the data moving through it — customer details, validated order, payment token, confirmation message.

Yourdon-DeMarco DFD on left and Gane-Sarson DFD on right side by side

Yourdon-DeMarco and Gane-Sarson

External entities, processes, data stores, and flows follow Yourdon-DeMarco conventions by default, with Gane-Sarson shape variants you can switch to.

Three numbered process circles 1.0, 1.1, 1.2 above two data store rectangles D1 and D2

Numbered Processes and Stores

Processes are numbered (1, 1.1, 1.2…) and data stores follow standard D1, D2 labeling so the diagram stays traceable across levels.

When to use the DFD maker

Use this tool for

  • STRIDE threat-modeling sessions where you need the trust boundaries visible before walking through Spoofing, Tampering, Repudiation, Information disclosure, Denial of service, and Elevation of privilege.
  • Security review documentation — show external entities, processes, and stores on one page so reviewers see the attack surface in a glance.
  • ETL and data-pipeline visualization — sources, transformations, destinations — for a data-engineering RFC.
  • Compliance artifacts (SOC 2 system descriptions, HIPAA security risk assessments) where the auditor specifically asks for a DFD-labeled diagram.

Use a different tool for

  • Step-by-step procedural logic — a flowchart shows order; DFDs intentionally don't.
  • Schema design — ER Diagram Generator describes tables and joins, not movement.
  • Per-request service interactions — Sequence Diagram Maker captures the call timing.
  • Strict trust-boundary annotation as part of the diagram — generate the DFD here, then overlay dashed boundary lines in Figma, Excalidraw, or Microsoft Threat Modeling Tool.

DFD Maker FAQ

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