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Gleek alternatives: 4 apps ranked by verified data

Facts checked Oct 25, 2026AppBreakup editorialHow we rank

Common reasons people leave Gleek: free plan limited to 5 files and 40 objects, and free diagrams are stored only in the browser. We ranked 4 alternatives by how directly each one replaces Gleek, then by reviews, real visits and how recently each app's facts were checked against its own website. Mermaid currently ranks first.

Quick comparison

#AppPricingOpen sourcePlatformsVerified factsScore
1PlantUML logoPlantUMLOpen sourceYesWeb, Windows, macOS +24 of 462.6
2D2 logoD2Open sourceYesWindows, macOS, Linux +15 of 557.2
  1. PlantUML logo

    1. PlantUMLTop pick

    Best for: Engineers documenting software with UML diagrams kept as text in the repo

    Open sourceSelf-hostableWeb, Windows, macOS, Linux, Self-hosted

    62.6

    score / 100

    Why switch from Gleek

    Deeper UML support and self-hosting, for free.

    Pros

    • Very broad UML coverage
    • Plugins for most IDEs and documentation tools
    • Can be self-hosted as a rendering server
    • Free and open source

    Cons

    • Default visual style looks dated
    • Local use needs Java installed
    • Syntax has many inconsistencies between diagram types
    Visit PlantUML Details and reviews
    How this score is calculated
    Editorial fit ×0.387
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is PlantUML a good Gleek alternative?

    Verified facts

    4 of 4 verified
    Open source
    Yes
    Checked Oct 25, 2026plantuml.com(opens source in a new tab)
    License
    LGPL-3.0 (repo); GPL and other builds offered
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Licensing options
    Several licences, GPL build is most complete
    Checked Oct 25, 2026plantuml.com(opens source in a new tab)
    In-browser rendering
    JavaScript rendering engine
    Checked Oct 25, 2026plantuml.com(opens source in a new tab)
  2. D2 logo

    2. D2

    Best for: Developers who want diagrams as code with more layout and styling control than Mermaid

    Open sourceWindows, macOS, Linux, Web

    57.2

    score / 100

    Why switch from Gleek

    Open-source diagram language with an offline CLI and polished output.

    Pros

    • Clean default output with themes and custom fonts
    • Multiple layout engines to choose from
    • Offline CLI with live-reload watch mode
    • Modular diagrams through imports

    Cons

    • Not rendered natively on GitHub
    • Smaller ecosystem than Mermaid or PlantUML
    • Still needs a CLI or plugin to render
    Visit D2 Details and reviews
    How this score is calculated
    Editorial fit ×0.369
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.1585
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is D2 a good Gleek alternative?

    Verified facts

    5 of 5 verified
    License
    MPL-2.0
    Checked Oct 25, 2026github.com(opens source in a new tab)
    Platforms
    macOS, Linux, Windows
    Checked Oct 25, 2026d2lang.com(opens source in a new tab)
    Project
    Independent, fiscally sponsored by Hack Club
    Checked Oct 25, 2026d2lang.com(opens source in a new tab)
    CLI
    Local CLI with watch mode
    Checked Oct 25, 2026d2lang.com(opens source in a new tab)
    Custom fonts
    Your own .ttf files
    Checked Oct 25, 2026d2lang.com(opens source in a new tab)

The best Gleek alternative for…

The highest-ranked app in this list for each need.

Mermaid logo

Best Gleek alternative for most people

Mermaid

Free and open source, with diagrams that render natively on GitHub.

PlantUML logo

Best Gleek alternative for a free option

PlantUML

Deeper UML support and self-hosting, for free.

dbdiagram.io logo

Best Gleek alternative for a free plan you can upgrade

dbdiagram.io

Specialised text-to-ERD tool if database diagrams are your main use.

D2 logo

Best Gleek alternative for open source

D2

Open-source diagram language with an offline CLI and polished output.

Mermaid logo

Best Gleek alternative for self-hosting

Mermaid

Free and open source, with diagrams that render natively on GitHub.

PlantUML logo

Best Gleek alternative for Mac

PlantUML

Deeper UML support and self-hosting, for free.

PlantUML logo

Best Gleek alternative for Windows

PlantUML

Deeper UML support and self-hosting, for free.

PlantUML logo

Best Gleek alternative for Linux

PlantUML

Deeper UML support and self-hosting, for free.

Mermaid logo

Best Gleek alternative for working in the browser

Mermaid

Free and open source, with diagrams that render natively on GitHub.

Gleek alternatives: common questions

What is the best alternative to Gleek?

Mermaid ranks first right now. Free and open source, with diagrams that render natively on GitHub. PlantUML and dbdiagram.io follow it in our ranking.

Is there a free alternative to Gleek?

Yes. Mermaid (open source), PlantUML (open source), dbdiagram.io (free plan + paid) and D2 (open source) have a free option. Check each app's verified facts for current plan limits.

Is there an open-source alternative to Gleek?

Yes: Mermaid, PlantUML and D2. Mermaid and PlantUML can also be self-hosted.

Which Gleek alternatives work on Linux?

PlantUML and D2 run on Linux.

Why do people switch from Gleek?

The complaints we hear most: free plan limited to 5 files and 40 objects; free diagrams are stored only in the browser; smaller community and fewer integrations.

How is this list ranked?

Every app is scored with the same published formula: how directly it replaces Gleek, reviews (weighted by verification), visits from AppBreakup, how recently its facts were checked against its own website, and reader votes.