If you want charts, diagrams, or visual explainers created from text, prompts, or code, there are now several strong options. Mermaid is the most widely known. But it's only one part of a broader landscape that includes Graphviz, PlantUML, D2, SVG, and QuickChart.

This guide compares them with a practical lens: auto-generation, flexibility, free usage, longevity, adoption, momentum, LLM compatibility, and real-world use cases.

An important theme runs through all of this: text-to-graphics is not just about generating an image once. It's about roundtripping too. In other words, how easy is it to edit, iterate, maintain, and regenerate the visual later? That matters a lot if you are working with an LLM. A generated PNG may look good at first, but it is much harder to tweak accurately later. A text-based source can be revised, versioned, and reused.

1) The Landscape

  • Diagram DSLs: Mermaid, Graphviz, PlantUML, D2
    (DSL = Domain-Specific Language)
  • Code-based: Python (Diagrams)
  • Output format: SVG
  • API-driven charts: QuickChart

Key distinction: structure diagrams vs data-driven charts.

More important distinction: some tools are much better for roundtripping than others. If you expect to come back later and refine the visual, text-based definitions usually beat direct image generation by a wide margin.

2) Comparison Table

Tool Type Text → Auto Flexibility LLM Friendly Dynamic / API Roundtripping / Editability
Mermaid JS DSL Yes Medium Excellent No Excellent
Graphviz DOT DSL Yes Very High Good Limited Good
PlantUML DSL Yes Very High Very Good Partial Very Good
D2 DSL Yes High Excellent Emerging Excellent
SVG Format No Very High OK Possible Mixed
QuickChart API Yes Charts only Excellent Best Very Good

3) Best Tool by Use Case

Use Case Best Tool Why Alternatives
Flowcharts Mermaid Fast, readable, widely supported, and easy to revise later D2, PlantUML
Sequence diagrams PlantUML Most expressive + mature, with strong maintainability Mermaid
System architecture diagrams D2 Clean layouts, modern syntax, and excellent roundtripping PlantUML, Mermaid
Marketecture diagrams D2 Better control with cleaner visuals while staying editable as text SVG (for polish), Mermaid (quick draft)
Dependency graphs / networks Graphviz Best layout algorithms for graph-heavy visuals D2
Gartner-style quadrant SVG Precise positioning matters more here, though roundtripping is weaker QuickChart (scatter), Mermaid (limited)
Bar / line / pie charts QuickChart Built for charts, easy JSON configs, and easy regeneration from updated data Chart.js (direct), SVG
Dynamic charts (API-driven) QuickChart URL-based rendering with live data and easy regeneration on demand Custom backend + SVG
Docs / blog diagrams Mermaid Embeds easily and stays maintainable over time D2
LLM-generated diagrams Mermaid / D2 Lowest error rate and easiest to iteratively refine QuickChart (for charts)
Pixel-perfect visuals SVG Full control, but weaker for ongoing iteration unless carefully structured Export from any tool

4) Why QuickChart Is Different

QuickChart's superpower is dynamic generation via URL parameters.

https://quickchart.io/chart?c=
  • No rendering pipeline
  • No frontend required
  • Works in emails, dashboards, APIs
  • Easy to regenerate from changed parameters or updated data

Think: prompt → JSON → URL → image

That makes QuickChart especially strong when the image is not a one-time asset, but a visual that needs to be regenerated repeatedly from new inputs.

5) How LLMs Change Things

  • Best: Mermaid, D2, QuickChart
  • OK: PlantUML
  • Harder: Graphviz, SVG

LLMs reduce friction, but structured text formats still win for iteration. That is the core roundtripping advantage. You can ask the LLM to adjust labels, reorder steps, update data, or restyle the output while preserving the underlying source. By contrast, once an LLM generates a flat image, accurate edits become much harder.

That is why the right comparison is not just image generation. It is text-to-graphics that remain editable.

6) Bottom Line

  • Default: Mermaid
  • Modern upgrade: D2
  • Complex diagrams: PlantUML
  • Graph layouts: Graphviz
  • Charts & dynamic: QuickChart
  • Final polish: SVG

Best workflow:
Prompt → Mermaid / D2 / QuickChart → export PNG/SVG → publish

If you expect to iterate, collaborate, or maintain the visual later, favor tools that preserve a clean text representation. That's the real advantage of text-to-graphics tools in the LLM era: not just generation, but reliable regeneration.