What diagram formats and syntax does this flow formatter support?

Our flow formatter supports three major diagram formats: Mermaid (ideal for flowcharts, sequence diagrams, Gantt charts, and state diagrams with simple, intuitive syntax), PlantUML (excellent for UML diagrams with extensive customization options), and Graphviz DOT (perfect for complex network diagrams with automatic intelligent layout algorithms). Each format has unique strengths - Mermaid offers the easiest learning curve for beginners, Graphviz excels at handling large, intricate diagrams with minimal manual adjustment, and PlantUML provides comprehensive UML diagram support. You can seamlessly switch between formats and even convert diagrams from one syntax to another while preserving the core structure and relationships.

How do I export my flow charts and what file formats are available?

Exporting your diagrams is straightforward with three professional output formats available. SVG (Scalable Vector Graphics) export produces resolution-independent graphics perfect for web embedding, technical documentation, and situations requiring lossless scaling - SVG files remain crisp at any zoom level and can be further edited in vector graphics software. PNG export generates high-quality raster images with 2x resolution scaling, ideal for presentations, email attachments, and situations requiring universal compatibility. PDF export creates print-ready documents with preserved layout and formatting, perfect for formal documentation, archival purposes, and professional reports. All exports maintain the visual fidelity of your rendered diagram, including colors, shapes, and text formatting.

Can I create complex multi-level diagrams with conditional branches and decision points?

Absolutely! The flow formatter fully supports sophisticated diagram structures including nested subgraphs for organizing related components, conditional branching with labeled decision paths, parallel process flows, swimlane diagrams for cross-functional workflows, and state machines with transitions. You can create decision points using diamond-shaped nodes with multiple outgoing paths labeled with conditions (like Yes/No or specific criteria). The tool handles complex scenarios such as loops, parallel execution paths, hierarchical structures, and interconnected systems. Use the template library to explore pre-built examples of advanced patterns including approval workflows, system architecture diagrams, algorithm flowcharts with multiple decision points, and business process models with exception handling paths.

Does the tool validate my diagram syntax and help me fix errors?

Yes, comprehensive syntax validation is built into every step of your workflow. The editor provides real-time error detection as you type, immediately highlighting syntax issues with precise error messages that explain exactly what went wrong and where. Common problems like unclosed brackets, invalid node identifiers, incorrect edge syntax, and format-specific errors are caught instantly with helpful guidance on how to fix them. The validation system is format-aware, understanding the specific rules and requirements of Mermaid, Graphviz DOT, and PlantUML syntax. You can manually trigger validation at any time using the Validate Syntax button, which performs a complete check and reports the results. The status bar continuously displays syntax validity, showing green checkmarks for valid code and red indicators with error counts when issues are detected, enabling you to write correct diagram code confidently.

How do I customize the appearance and layout of my flow charts?

Extensive customization options give you complete control over diagram aesthetics and structure. Choose from multiple built-in themes (Default, Dark, Forest, Neutral) that apply professional color schemes and styling to your entire diagram instantly. Control flow direction with four orientation options: Top-to-Bottom (traditional flowchart style), Left-to-Right (great for timeline and process flows), Bottom-to-Top (inverted hierarchy), and Right-to-Left (alternative reading direction). The Auto Layout feature intelligently optimizes node positioning to minimize edge crossings, maintain consistent spacing, and create visually balanced diagrams without manual adjustment. The Beautify Code function automatically formats your source code with proper indentation and structure for maximum readability. Beyond these automated features, each diagram format supports inline styling including custom colors, node shapes (rectangles, circles, diamonds, rounded boxes), line styles (solid, dashed, dotted), edge labels, and text formatting, giving you fine-grained control when needed.

Can I import existing diagram files or load diagrams from URLs?

File import capabilities are comprehensive and flexible. The Upload feature accepts multiple file formats including .txt (plain text), .mmd (Mermaid format), .puml (PlantUML format), .dot (Graphviz format), and .flow (generic flow files), with a maximum file size of 2MB ensuring compatibility with even large, complex diagrams. Simply click the Upload button, select your file, and the diagram code loads instantly into the editor ready for preview and editing. The Load URL feature enables you to import diagram code directly from any publicly accessible web URL, perfect for loading examples from documentation, importing shared diagrams from GitHub repositories or gist files, or pulling diagram definitions from your own web storage. Both import methods preserve all formatting, structure, and syntax, allowing you to immediately start editing or rendering the imported content without any conversion steps.

What is the template library and how can it help me get started quickly?

The template library contains professionally designed, production-ready diagram templates covering the most common use cases across different diagram types. For Mermaid format, templates include Basic Flowcharts (simple process flows with decision points), Sequence Diagrams (system interaction timelines perfect for API documentation), State Diagrams (state machine visualizations for system behavior modeling), and Gantt Charts (project timelines with tasks and dependencies). Graphviz templates feature Network Diagrams (connected node graphs for system architecture) and Tree Structures (hierarchical organization charts). PlantUML templates include Class Diagrams (UML class relationships for software design). Each template comes with a clear title, descriptive explanation of its use case, and complete working code that you can immediately customize. Templates serve as learning tools showing syntax patterns and best practices, starting points that you can adapt to your specific requirements, and reference examples demonstrating advanced features like styling, layout options, and complex relationships. Simply click any template to load it into the editor, then modify the content while preserving the proven structure and formatting.

Are there size limits for diagrams and how well does the tool handle large, complex visualizations?

The flow formatter efficiently handles diagrams up to 2MB of source code, which accommodates hundreds of nodes and edges comfortably - far exceeding the needs of most practical use cases including comprehensive system architectures, detailed business process maps, and large organizational hierarchies. For very large diagrams, initial rendering may take a few seconds as the layout algorithms optimize node positioning and edge routing, but the tool remains fully responsive throughout. Performance optimization techniques include intelligent caching, incremental rendering when possible, and memory-efficient processing. If you encounter performance issues with extremely large diagrams (rare in practice), consider breaking them into smaller, focused sub-diagrams that each illustrate a specific aspect of the system, using hierarchical organization with high-level overview diagrams that link to detailed component diagrams, or employing the Auto Layout feature to simplify complex manual positioning. The zoom controls (zoom in, zoom out, fit to screen) make navigating large diagrams effortless, and the grid toggle helps maintain spatial orientation in complex visualizations.

Flow Formatter Online - Professional Flow Chart Editor, Diagram Maker & Converter

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Complete Guide to Professional Flow Chart Creation

What Problems Does This Flow Formatter Solve?

Creating professional flow charts traditionally requires expensive desktop software, steep learning curves, and tedious manual node positioning. Our online flow formatter eliminates these pain points by providing an intuitive, free, browser-based solution that works on any device. Whether you're a developer documenting system architecture, a business analyst mapping processes, a project manager creating workflows, or a student learning algorithm design, you need a tool that combines ease of use with professional output quality. This formatter addresses the common frustrations of inconsistent formatting, time-consuming layout adjustments, syntax errors without helpful feedback, limited export options, and the inability to quickly iterate on diagram designs. With real-time preview, automatic syntax validation, intelligent auto-layout, multiple export formats, and support for industry-standard diagram languages, you can focus on your content and logic rather than wrestling with diagram tools.

Step-by-Step: Creating Your First Flow Chart

Choose Your Diagram Format: Select from the format dropdown menu. Mermaid is recommended for beginners due to its simple, readable syntax and comprehensive diagram type support. Graphviz DOT excels for complex network diagrams requiring sophisticated automatic layout. PlantUML is ideal if you need UML-specific diagrams or extensive customization. Each format has unique strengths - try the templates to see examples.
Write or Import Your Diagram Code: Start typing directly in the syntax-highlighted code editor, which helps prevent errors with color-coding and auto-indentation. Alternatively, click Upload to import existing diagram files (.mmd, .dot, .puml, .txt formats accepted, max 2MB), use Load URL to fetch diagram code from any public web address, or click Templates to browse pre-built examples you can customize. The editor supports standard keyboard shortcuts and provides line numbers for easy reference.
See Real-Time Preview: Your diagram renders automatically in the preview pane as you type (with a 1-second delay to avoid excessive re-rendering). Changes appear instantly, showing exactly how your flow chart will look when exported. The preview includes zoom controls and a toggleable grid background for precise visual alignment. If you prefer manual control, disable auto-render and use the Render Diagram button instead.
Customize Appearance and Layout: Apply professional themes using the Theme dropdown - Default provides clean, neutral styling; Dark offers high-contrast visibility; Forest gives earthy, organic colors; Neutral creates minimal, professional aesthetics. Adjust the flow direction (Top-Bottom for traditional flowcharts, Left-Right for timeline processes, Bottom-Top for inverted hierarchies, Right-Left for alternative orientations). Use Auto Layout to let algorithms optimize node positions automatically, reducing edge crossings and creating balanced spacing. Run Beautify Code to automatically format your source code with proper indentation and structure.
Validate Syntax for Error-Free Diagrams: The status bar continuously shows syntax validity in real-time with green checkmarks for valid code and red indicators when errors are detected. Click Validate Syntax to trigger a comprehensive check that reports all issues with detailed error messages, line numbers, and helpful suggestions for fixes. Common errors like unclosed brackets, invalid node connections, and syntax mistakes are caught immediately with clear explanations, helping you learn the syntax while building your diagram.
Export in Professional Formats: When your diagram is ready, export using the format that best suits your needs. Export SVG creates scalable vector graphics perfect for web embedding, further editing in design software, and situations requiring resolution-independent graphics. Export PNG generates high-quality 2x resolution images ideal for presentations, email attachments, documentation, and sharing on platforms with limited SVG support. Export PDF produces print-ready documents with preserved layout and formatting, excellent for formal reports, archival purposes, and situations requiring locked layouts. You can also Download Code to save the source as a text file for version control, backup, or sharing with collaborators.

Comprehensive Diagram Type Support

Flowcharts: Create traditional process flowcharts with standard shapes - rectangles for processes, diamonds for decisions, rounded rectangles for start/end points, and arrows showing flow direction. Perfect for documenting business processes, algorithm logic, troubleshooting guides, and decision trees. Add labels to arrows to show conditions or outcomes.

Sequence Diagrams: Visualize time-based interactions between systems, components, or actors. Show message passing, API calls, function invocations, and asynchronous communication patterns. Essential for documenting distributed systems, microservice architectures, user authentication flows, and system integration points. Include activation boxes to show when components are active.

State Diagrams: Model state machines showing how systems transition between different states based on events or conditions. Perfect for user interface behavior, protocol implementations, game logic, and any system with distinct operational modes. Define states, transitions, entry/exit actions, and guard conditions.

Entity Relationship Diagrams (ERD): Design database schemas showing entities, attributes, and relationships with cardinality notation. Essential for database design, data modeling, and documenting existing database structures. Support for one-to-one, one-to-many, and many-to-many relationships with identifying and non-identifying connections.

Gantt Charts: Plan and track projects with visual timeline representations. Show tasks, durations, dependencies, milestones, and progress tracking. Ideal for project management, sprint planning, resource allocation, and communicating schedules to stakeholders. Set task dependencies to show critical paths.

Class Diagrams: Document object-oriented software design with classes, attributes, methods, and relationships. Show inheritance, composition, aggregation, and association between classes. Essential for software architecture documentation, design reviews, and communicating system structure to development teams.

Network and System Architecture Diagrams: Visualize system components, servers, databases, services, and their interconnections. Perfect for cloud architecture, microservices documentation, infrastructure planning, and security diagrams showing trust boundaries and data flows.

Advanced Features That Make Diagram Creation Effortless

Intelligent Auto-Layout Engine: Automatically positions nodes and routes edges to create visually balanced, readable diagrams. The algorithm minimizes edge crossings, maintains consistent spacing, groups related nodes, and respects hierarchical relationships. Particularly powerful for complex diagrams with dozens of nodes where manual positioning would be tedious and error-prone.

Real-Time Syntax Validation: Catches errors as you type, not when you try to render. The validation engine understands format-specific rules for Mermaid, DOT, and PlantUML, providing contextual error messages that explain what went wrong and how to fix it. Learns common patterns to predict potential issues before they become errors.

Code Beautification and Formatting: Automatically formats your diagram code with proper indentation, consistent spacing, and logical structure. Makes code more readable, easier to maintain, and helps teams establish consistent formatting standards. Particularly useful when importing diagrams from external sources or cleaning up quickly-written code.

Template Library for Quick Starts: Pre-built, professionally designed templates cover the most common diagram types. Each template includes complete working code demonstrating syntax patterns, best practices, and advanced features. Use templates as learning tools to understand format capabilities, starting points for your own diagrams, or reference examples when you need to remember specific syntax.

Multi-Format Support and Conversion: Work with industry-standard diagram languages: Mermaid (simple syntax, great for quick diagrams), Graphviz DOT (powerful layout engine for complex graphs), and PlantUML (comprehensive UML support). While direct automated conversion between formats has limitations due to syntax differences, the template library helps you recreate diagrams in different formats when needed.

Flexible Import and Export Options: Import diagrams by uploading files from your computer, loading from public URLs (perfect for documentation sites, GitHub, or shared repositories), or pasting code directly. Export finished diagrams as SVG (scalable vectors), PNG (universal images), PDF (print-ready documents), or download the source code as text files for version control and collaboration.

Visual Customization Options: Beyond basic formatting, add custom colors to nodes and edges, choose from multiple node shapes (rectangles, circles, diamonds, rounded boxes, cylinders for databases), apply different line styles (solid, dashed, dotted), add styling classes, and use inline styles for fine-grained control over individual elements.

Zoom and Navigation Controls: Navigate large diagrams easily with zoom in/out buttons, zoom to fit functionality that automatically scales diagrams to fill the preview area, and a toggleable grid background that helps with visual alignment. Pan large diagrams by scrolling, and the zoom level indicator shows current scaling percentage.

Frequently Asked Questions - Everything You Need to Know

Q: Which diagram format should I choose for my specific use case? A: Choose Mermaid if you're new to diagram-as-code, need quick flowcharts or sequence diagrams, want simple syntax that's easy to read and write, or prefer a format with active community support and extensive documentation. Mermaid is excellent for software documentation, README files, and collaborative projects. Choose Graphviz DOT when working with complex network diagrams, large graphs with many interconnected nodes, situations where automatic layout optimization is critical, or when you need fine-grained control over node positioning algorithms. DOT excels at system architecture diagrams, dependency graphs, and visualization of complex relationships. Choose PlantUML for formal UML diagrams (use case, class, component, deployment diagrams), when you need extensive customization through skinparams, or when working in Java development environments where PlantUML has native integration. Consider your team's familiarity - if colleagues already know a format, stick with it for easier collaboration. Q: How do I create decision points, conditional branches, and loops in my flowcharts? A: In Mermaid, use curly braces with a question mark to create diamond-shaped decision nodes: A{Is condition true?}. Connect branches with labeled edges using pipe symbols: A -->|Yes| B and A -->|No| C. For loops, simply create an edge that points back to an earlier node: D --> A creates a loop back to the start. In Graphviz DOT, use shape="diamond" attribute for decision nodes and label edges with [label="condition"] syntax. For complex branching, consider using subgraphs to group related decision paths. The template library includes examples showing common conditional flow patterns including if-then-else structures, switch-case logic, and nested decisions. Practice with templates first to understand the syntax, then adapt the patterns to your specific logic. Q: Can I collaborate with team members on flow chart creation and editing? A: While the tool doesn't support real-time simultaneous editing, it's designed for easy collaboration workflows. Share diagrams by using the Download Code button to save source files, then commit them to version control systems (Git, SVN) where team members can track changes, review modifications, and merge updates just like code. The text-based format makes diffs readable and merge conflicts resolvable. Alternatively, copy diagram code to the clipboard and share via messaging tools, email, or documentation platforms. Team members can use Load URL to import diagrams from shared web locations like GitHub gists, internal wikis, or cloud storage with public links. For review workflows, export diagrams as PNG or PDF for stakeholder feedback, then incorporate changes into the source code. The format's readability means non-technical reviewers can often understand and suggest edits even to the raw code. Q: How do I effectively manage and organize large, complex diagrams with many nodes? A: Large diagram management requires strategic organization. Use subgraphs or clusters to group related nodes into logical sections - for example, group all database-related nodes together, separate frontend from backend components, or organize by system layers. This improves both visual clarity and code maintainability. Apply the Auto Layout feature to optimize positioning automatically rather than manually adjusting dozens of nodes. Use hierarchical design where a high-level overview diagram links to detailed component diagrams - think of it like documentation chapters rather than one massive page. Leverage consistent naming conventions for nodes so related elements are easy to find in code. For Mermaid, use the direction control (LR vs TB) to spread out crowded diagrams. Consider simplifying by abstracting less important details into labeled connections rather than explicit nodes. The zoom controls make navigation easier, but if a diagram becomes unwieldy even with zoom, that's a signal to break it into multiple focused diagrams. Remember: clarity trumps comprehensiveness - multiple clear diagrams are more valuable than one overwhelming diagram. Q: Which export format should I use for different scenarios and purposes? A: Choose SVG when embedding diagrams in web pages (HTML documentation, wikis, blogs), publishing in digital documents where zoom quality matters, planning to further edit diagrams in vector graphics software (Illustrator, Inkscape), or when file size efficiency is important (SVG is often smaller than PNG for simple diagrams). SVG maintains perfect quality at any zoom level and text remains selectable. Choose PNG for presentations (PowerPoint, Keynote, Google Slides), email attachments where universal compatibility is essential, uploading to platforms that don't support SVG (some social media, forums), printing at fixed sizes, or when you need raster images with transparency. Our PNG export uses 2x resolution for crisp display on high-DPI screens. Choose PDF for formal documentation and reports, archival purposes where layout must remain unchanged, printing at various sizes while maintaining quality, situations requiring page layout control, or when distributing diagrams where editing should be prevented. PDFs embed fonts and preserve exact appearance. For collaboration and version control, download the source code as text files - this allows tracking changes, code reviews, and easy editing. Q: How do I customize colors, shapes, styles, and visual appearance of diagram elements? A: Customization approaches vary by format. In Mermaid, apply styling using triple colons: A:::customStyle then define styles in a classDef section: classDef customStyle fill:#f9f,stroke:#333,stroke-width:2px. For individual nodes, use inline syntax: style A fill:#f96,stroke:#333,stroke-width:4px. In Graphviz DOT, add attributes directly to nodes: A [color=red, style=filled, fillcolor=lightblue, shape=box]. Control edge appearance with attributes like [color=blue, style=dashed, penwidth=2.0]. PlantUML uses skinparam commands for global styling: skinparam backgroundColor transparent or skinparam classBackgroundColor LightYellow. The theme selector provides pre-designed color schemes, but custom styling overrides theme defaults. Available shapes include box/rectangle (standard nodes), circle/ellipse (connectors, states), diamond (decisions), rounded rectangles (start/end), cylinder (databases), and format-specific shapes like actors in sequence diagrams. Experiment with templates to see styling examples, then adapt the patterns to your brand colors or visual preferences. Remember that while customization enhances appearance, excessive styling can reduce readability - prioritize clarity over decoration. Q: How do I create swimlane diagrams showing cross-functional processes and responsibilities? A: Swimlane diagrams show process flows across different actors, departments, or systems, with each "lane" representing a different responsibility area. In Mermaid, create swimlanes using subgraphs with descriptive titles:

subgraph Customer
  A[Place Order]
end
subgraph Warehouse
  B[Pick Items]
end

. Connect nodes across swimlanes with normal edges. For sequence diagrams, Mermaid natively supports participants which act as swimlanes:

participant Customer
participant System
participant Database

with messages flowing between them. In Graphviz, use clustered subgraphs with labels:

subgraph cluster_sales {
  label="Sales Department";
  A -> B;
}

. Organize clusters vertically or horizontally using rankdir and rank=same to control layout. PlantUML has built-in swimlane support in activity diagrams with the partition keyword:

partition Customer {
  :Submit Request;
}

. The template library includes swimlane examples you can adapt. Key to good swimlane diagrams: keep lanes to 3-5 for readability, clearly label each lane with the actor/department name, use consistent color coding within lanes, minimize cross-lane connections to show clear handoffs, and include decision points to show where processes branch based on conditions. Q: Are there size or complexity limits, and what happens with very large diagrams? A: The formatter accepts source code files up to 2MB, which comfortably handles diagrams with hundreds of nodes and edges - far exceeding most practical use cases. A typical complex system architecture diagram with 100 nodes and 150 connections uses only about 10-20KB of source code, meaning the 2MB limit provides ample headroom. For very large diagrams (100+ nodes), initial rendering may take 2-5 seconds as layout algorithms calculate optimal positioning and route edges, but the interface remains responsive. The tool uses performance optimizations including incremental rendering when possible, efficient DOM updates, and memory management to handle complexity. If you encounter performance issues (rare in practice), consider these strategies: break monolithic diagrams into focused sub-diagrams, each illustrating a specific subsystem or process phase; create a hierarchical structure with a high-level overview linking to detailed component diagrams; use the Auto Layout feature rather than manual positioning to reduce rendering complexity; simplify visual styling (complex custom styles on many nodes can impact performance); or export to SVG and view in dedicated SVG software for extremely complex visualizations. The zoom controls, grid toggle, and pan functionality make navigating large diagrams comfortable even when they fill multiple screen-widths.

Need Help or Have Questions? Visit our Support Center for troubleshooting assistance, feature requests, bug reports, and general feedback. We're continuously improving the tool based on user input and welcome your suggestions for new features or diagram format support.