blockdiag
blockdiag generates block-diagram image from text
Decision gist · record as of 2026-08-14
Yes, if you need a lightweight, text-driven block-diagram generator and can tolerate an abandoned codebase. The package is stable and has no known vulnerabilities, but expect no bug fixes or feature updates. It works reliably for basic diagrams on supported Python versions. Avoid it if you require active maintenance, support for newer Python versions, or ongoing feature development.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.7 or later; Pillow 3.0 or later is a runtime dependency.
- Low install friction with a pure-Python wheel distribution.
- However, the package is abandoned—last release was 2021-12-06, with no active maintenance despite the repository remaining unarchived.
License · maintenance · safety
Apache License 2.0 (permissive) — Apache License 2.0 is permissive, allowing commercial and private use with minimal restrictions. You may use, modify, and distribute blockdiag freely as long as you include a copy of the license.
last release 2021-12-06 (1712 days) · last repo commit 2023-08-13 · 241 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 114,416 downloads/mo, #12,295 on PyPI
Alternatives
Verify before relying
pip install blockdiag
Create a file `diagram.diag`:
diagram admin {
top_page -> config -> config_edit -> top_page;
}
Then run: blockdiag diagram.diag
Output: diagram.png- Whether the package works reliably with Python versions beyond 3.9 (classifiers list only up to 3.9).
- Current state of optional dependencies (reportlab, wand/imagemagick) and whether PDF export still functions.
- Whether the dot-like syntax is fully documented and stable for new users.
What it is and what it does
blockdiag is a text-to-diagram generator that converts a simple dot-like specification language into block-diagram images. You write a plain-text file describing nodes and transitions, then run blockdiag to produce PNG output (or optionally PDF with additional dependencies). It's designed for system administrators and developers who need to document workflows, system architectures, or process flows without using a graphical editor.
The package depends on Pillow for image rendering, funcparserlib for parsing the specification syntax, webcolors for color handling, and setuptools. It supports UTF-8 multilingual labels on nodes. The main limitation is that the project is no longer actively maintained—the last release was in December 2021, so bugs and compatibility issues with newer Python versions or dependencies may not be addressed.
Use it for
- Document system administration workflows or process flows as text-based diagrams that can be version-controlled.
- Generate architecture diagrams for technical documentation without requiring a GUI tool.
- Create flowcharts for application logic or user journeys in a reproducible, text-driven format.
- Embed diagram generation into build pipelines or documentation systems that consume text specifications.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need a lightweight, text-driven block-diagram generator and can tolerate an abandoned codebase.
The package is stable and has no known vulnerabilities, but expect no bug fixes or feature updates. It works reliably for basic diagrams on supported Python versions. Avoid it if you require active maintenance, support for newer Python versions, or ongoing feature development.
Install
blockdiag on PyPI
Before you install
Low install friction with a pure-Python wheel distribution. However, the package is abandoned—last release was 2021-12-06, with no active maintenance despite the repository remaining unarchived.
Requires Python 3.7 or later; Pillow 3.0 or later is a runtime dependency.
License in practice
Apache License 2.0 is permissive, allowing commercial and private use with minimal restrictions. You may use, modify, and distribute blockdiag freely as long as you include a copy of the license.
Quickstart
pip install blockdiag
Create a file `diagram.diag`:
diagram admin {
top_page -> config -> config_edit -> top_page;
}
Then run: blockdiag diagram.diag
Output: diagram.pngVerify before relying
- Whether the package works reliably with Python versions beyond 3.9 (classifiers list only up to 3.9).
- Current state of optional dependencies (reportlab, wand/imagemagick) and whether PDF export still functions.
- Whether the dot-like syntax is fully documented and stable for new users.
Package facts
| License | Apache License 2.0 permissive |
| Python support | Supports the current Python release >=3.7 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 4 packagessetuptoolsfuncparserlibPillowwebcolors |
| Maintenance | Abandoned 1,712 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 114,416 / month, #12,295 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableIntended Audience :: System AdministratorsLicense :: OSI Approved :: Apache Software LicenseProgramming Language :: PythonProgramming Language :: Python :: 3.7Programming Language :: Python :: 3.8Programming Language :: Python :: 3.9Topic :: Software DevelopmentTopic :: Software Development :: DocumentationTopic :: Text Processing :: Markup |
Evidence: blockdiag-3.0.0-py3-none-any.whl
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See also sphinxcontrib-blockdiag · mkdocs-kroki-plugin · mermaid-builder · schemdraw · mkdocs-mermaid2-plugin · pydot-ng · sphinxcontrib-mermaid · markdown-inline-graphviz-extension · django-diagram · diagrams