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Sequence Diagram Generator Sequence Diagrams

Describe an interaction and get a clean, labeled UML sequence diagram in seconds, complete with vertical lifelines, horizontal message arrows, activation bars, and loop or alt fragments. Document software flows without touching a diagramming tool.

✓Lifelines and activation bars✓Loops, alt, and opt fragments✓Request and return arrows✓Slide and doc readyLast updated: 2026-09-25

Sequence Diagram Examples

Browse sequence diagrams made with Figviz, or generate your own above

User Login Authentication

A login flow showing the User, Browser, Auth Server, and Database exchanging credentials and returning a JWT token.

authenticationloginJWT

Online Payment Checkout

A checkout sequence covering the Customer, Frontend, Payment Gateway, and Order Service with confirmation steps.

paymentcheckoute-commerce

API Request-Response

A REST API call chain from Client through API Gateway to Microservice and back, with status codes labeled.

APIRESTmicroservice

E-Commerce Order Placement

An order placement flow across Customer, Cart Service, Inventory Service, and Shipping Service.

orderinventoryshipping

Loop and Alt Fragments

A sequence demonstrating loop and alt combined fragments for retry logic and conditional branching.

loopaltfragments

Simple Two-Actor Sequence

A clean two-actor sequence diagram showing the core UML elements: lifelines, messages, and activation bars.

basiclifelinestwo-actor

Sequence diagram prompts you can copy

Start with a common interaction flow, then replace the actors and messages with your own system details.

Password reset flow

A user-facing journey with an expiring token and a conditional error branch.

Create a UML sequence diagram for a password reset flow. Actors: User, Web App, Auth API, Email Service, Database. Flow: User requests reset, Web App sends email address to Auth API, Auth API checks Database, creates a one-time token, asks Email Service to send a reset link, then returns confirmation. In an alt fragment, show unknown email returning a generic confirmation without sending a link. Show lifelines, activation bars, solid request arrows, dashed returns, and message labels. White background.

File upload with virus scan

A service flow with asynchronous processing and a status callback.

Create a UML sequence diagram for a document upload with virus scanning. Actors: User, Browser, Upload API, Object Storage, Scan Worker, Notification Service. Flow: Browser uploads a file to Upload API, API stores it in Object Storage and queues Scan Worker, worker scans the file, then an alt fragment shows [clean] marking it available and notifying User versus [infected] quarantining it and notifying User. Include asynchronous arrows for queued work, activation bars, and dashed return messages. Classic UML style, white background.

Inventory reservation retry

A purchase flow that uses loop and alt fragments.

Create a UML sequence diagram for inventory reservation during checkout. Actors: Checkout Service, Inventory Service, Database, Payment Service. Checkout Service tries to reserve stock. Use a loop fragment for up to 3 database retry attempts after a conflict. Use an alt fragment: [stock reserved] charge Payment Service and return order confirmation; [out of stock] release any reservation and return an unavailable message. Show all lifelines, activation bars, request arrows, and return arrows. White background.

Editorial evidence

How this page was reviewed

Reviewed as a visual sequence-diagram drafting workflow. The page now requires verification against the actual implementation and the UML specification before documentation use. Reviewed 2026-09-25.

Important limitations

The generator creates an image from the prompt; it does not inspect code, traces, API contracts, or runtime behavior.
AI-generated message order, arrow direction, labels, activation bars, and combined fragments can be incomplete or incorrect.
The PNG is not editable Mermaid, PlantUML, or UML model source and cannot stay synchronized with code automatically.

Sources used for review

About the Unified Modeling Language Specification Version 2.5.1 — Object Management Group
Unified Modeling Language 2.5.1 Specification — Object Management Group

What is a sequence diagram generator?

A sequence diagram generator turns a written interaction into a visual draft with actors, lifelines, messages, and activation bars. Figviz interprets plain language, so you can sketch a login flow, API call chain, or checkout process without writing diagram syntax. Verify message order, labels, fragment boundaries, and UML notation against the implemented system before using the image as technical documentation.

How to make a sequence diagram

List the actors or systems involved (for example: User, Browser, Auth Server, Database).

Write the messages in order, from the first trigger to the final response.

Note any return values, HTTP status codes, or data passed back.

Mention loops, alt branches, or opt blocks if the flow has conditions or retries.

Choose a style (Classic, Colorful, or Minimal) and generate.

Refine the prompt if any step is missing or out of order, then export.

Sequence diagram elements: lifelines, messages, activation bars, and fragments

Lifelines: vertical dashed lines that represent each actor or system for the duration of the interaction.

Messages: horizontal solid arrows showing a call or signal sent from one lifeline to another, labeled with the operation name.

Return arrows: dashed horizontal arrows showing the response or return value flowing back.

Activation bars: narrow rectangles on a lifeline showing when that actor is actively processing.

Combined fragments: labeled boxes around a section of the diagram to show loops (loop), conditional branches (alt), optional steps (opt), or parallel flows (par).

Self-messages: arrows that loop back to the same lifeline, showing an internal operation or recursive call.

Tips for clear sequence diagrams

Keep actor names short and consistent between the description and the diagram. Always write messages in chronological order top to bottom, the way a reader follows the diagram. Specify return values explicitly (for example "returns 200 OK with JSON") so the dashed arrow gets a useful label rather than a generic one. If a section repeats or branches, name the fragment type (loop, alt) and its condition in your prompt. For large flows, break them into sub-flows and generate one diagram per scenario rather than one giant diagram that is hard to read.

Sequence diagrams in software documentation

Sequence diagrams can clarify runtime behavior in design docs, API references, and architecture decision records. Figviz creates a visual draft from a prose description, but it does not inspect source code or update itself when the system changes. Compare the output with traces, API contracts, or the current implementation before publishing it. The UML diagram guide explains how sequence diagrams relate to other UML diagram types.

Frequently asked questions

A sequence diagram generator creates a visual draft from a description of an interaction. With Figviz you describe the actors and messages, and the AI draws lifelines, arrows, activation bars, and fragment boxes. Verify the result against the real interaction before using it in documentation.

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