tldraw
Leading#5 in Open sourcehigh confidence
Infinite-canvas whiteboard SDK (~49.2k★) — the toolkit developers build collaborative diagramming apps on.Our read
Why it ranks #5
Strong developer adoption at ~49.2k GitHub stars and a polished canvas SDK, but it ranks fifth because it is a source-available application toolkit rather than an out-of-box architecture-diagram format.Here is the catch
the SDK is source-available, not permissively open-source
production use requires a license key after the 100-day trial
developers must build the architecture semantics, icons and workflows themselves
Does this well
widely adopted, polished foundation for building custom collaborative diagram apps
deep customization across shapes, tools, storage and interface
active project with strong developer documentation
Pricing
Checked by hand on 2026-07-23. Prices in this category change often — if this looks wrong, it probably is.
Key features
extensible React infinite-canvas SDKcustom shapes, tools and UImultiplayer sync and persistence primitivesimage export and Mermaid integration
Sources we read
Quick facts
More in this area
The rest of the Open source column.- 1MermaidThe de-facto text-to-diagram standard (~89.4k★) — natively rendered in GitHub/GitLab Markdown, making it the default diagram-as-code format agents produce for architecture, flow and sequence diagrams.
- 2ExcalidrawThe dominant open-source virtual whiteboard (~128.3k★) — hand-drawn aesthetic, hugely used for freeform architecture sketches and system diagrams.
- 3Diagrams (mingrammer)The leading diagram-as-code library for cloud/system architecture (~42.5k★) — draw AWS/GCP/Azure/Kubernetes architecture from Python.
- 4D2Fast-rising modern diagram scripting language (~24.8k★) — cleaner syntax than PlantUML with strong automatic layout.
- 6PlantUMLThe long-standing text-to-UML workhorse (~13.2k★) — most complete UML coverage, ubiquitous in enterprise toolchains despite dated visuals.
- 7C4-PlantUMLThe standard way to render C4-model software architecture diagrams as code (~7.4k★) — the go-to for C4 + text.