Free Online UML
Diagram Maker
Create professional UML diagrams directly in your browser or desktop app.
Fast, local-first, zero installation required.
Everything you need to create UML diagrams
A complete browser-based UML workspace without unnecessary complexity, accounts, or subscriptions.
Class Diagrams
Design classes, interfaces, abstract classes, enums, attributes, methods, visibility indicators, and standard UML relationships.
Use Case Diagrams
Map actors, system boundaries, use cases, «include», and «extend» relationships to define software scope clearly.
Sequence Diagrams
Illustrate interaction message flows over time with lifelines, synchronous calls, asynchronous replies, and activation boxes.
Activity Diagrams
Model algorithmic execution flows, business logic, parallel fork/join operations, decision branches, and swimlanes.
State Machine Diagrams
Capture lifecycle states, initial/final states, state transitions, and event triggers for reactive systems.
Component Diagrams
Represent software modules, microservice boundaries, provided/required ports, and architectural dependencies.
Deployment Diagrams
Model physical hardware topology, cloud nodes, server instances, container execution environments, and networks.
Package Diagrams
Organize large codebase architectures into hierarchical namespaces, module layers, and subpackages.
Start faster with templates
Battle-tested architectural templates ready to open, customize, and export instantly.
E-commerce System Architecture
Complete e-commerce domain model with Customer, Order, OrderItem, and PaymentProcessor interfaces with multiplicity constraints.
Hospital Management System
Clinical inheritance hierarchy with abstract Person, Doctor, Patient, Nurse, Hospital, and Department composition.
Online Banking System
ATM and mobile banking user interactions with Customer, Bank Clerk, and Verification System actor boundary rules.
Work Online.
Keep Working Offline.
UML Studio runs directly in your browser and installs seamlessly to your macOS dock, Windows desktop, or Linux application menu. Once cached, it works completely without internet access.
- ✓Zero Cloud Server: 100% client-side execution with IndexedDB storage.
- ✓Standalone Desktop Experience: Fullscreen window without browser address bars.
- ✓Offline Project Persistence: All changes autosave locally in real time.
Your diagrams stay on your device
FreePDFly UML is designed from the ground up for total privacy. Unlike cloud drawing SaaS tools that require server accounts, all diagram parsing, rendering, and project persistence happen locally in your browser session.
No Account Required
Zero login, zero passwords, zero tracking pixels on diagram content.
Local Autosave
Saved directly to your browser's IndexedDB engine automatically on every edit.
No Cloud Dependency
No risk of downtime, subscription paywalls, or third-party data breaches.
Works Offline
Full modeling toolbox remains completely functional without network connectivity.
How it works
Create professional engineering documentation in three frictionless steps.
Choose a diagram
Start with a blank canvas or pick from our library of Class, Sequence, Use Case, and Activity templates.
Build your model
Drag classes, actors, lifelines, and connect them with standard UML arrows, multiplicities, and properties.
Export or save locally
Export high-res PNG, vector SVG, or paginated PDF documents with a single click.
Export your diagrams your way
Publish diagrams straight into engineering wikis, GitHub repos, technical RFCs, or client presentations.
High-Res PNG
Crisp raster images ready for Slack, Notion, and Jira issues.
Vector SVG
Infinitely scalable vector format ideal for website architecture diagrams.
Paginated PDF
Clean print-ready documentation for software specification documents.
Local JSON Backup
Complete raw project file for backup, restore, and team sharing.
Keep all your diagrams organized
Multi-project management stored locally in your browser IndexedDB engine.
Frequently Asked Questions
Common questions about FreePDFly UML, offline capabilities, export options, and privacy.
What is a UML diagram maker?▼
A UML (Unified Modeling Language) diagram maker is a visual modeling tool that enables software engineers, architects, and product teams to design and specify the structure, behaviors, interactions, and physical deployment of software systems.
Is UML Studio free?▼
Yes, UML Studio is 100% free with no trial periods, no credit cards, and no feature gates. All modeling features and exports are completely unrestricted.
Can I use UML Studio offline?▼
Yes! UML Studio is a Progressive Web App (PWA). You can click "Add to Desktop" or "Install App" to install it onto macOS, Windows, Linux, Android, or iOS. All assets and databases work fully offline.
Are my UML diagrams stored online?▼
No. All diagrams and projects are stored exclusively in your local browser's IndexedDB database. Your proprietary software architectures never leave your device.
Can I export UML diagrams as PDF, SVG, and PNG?▼
Yes. You can export high-resolution PNGs, infinitely scalable vector SVGs, paginated PDFs, or raw JSON project backups anytime directly from the File and Export menus.
What UML diagram types are supported?▼
UML Studio supports Class Diagrams, Use Case Diagrams, Sequence Diagrams, Activity Diagrams, State Machine Diagrams, Component Diagrams, Deployment Diagrams, and Package Diagrams.
Do I need an account to use UML Studio?▼
No account, email, or registration is required. You can launch the editor immediately with a single click.
Start Building Your UML Diagram
Create professional UML diagrams for free — directly in your browser. No credit card, no sign-up, 100% free forever.