Comic Library Utilities (CLU)

A self-hosted comic library manager for Docker — bulk CBR to CBZ conversion, a full CBZ editor, ComicInfo.xml metadata from Metron and ComicVine, a built-in web reader, and download automation.

Comic Library Utilities (CLU) is a self-hosted web app for organizing, repairing and reading a digital comic collection. It runs in Docker, points at the folders your comics already live in, and gives you the bulk tools you would otherwise write scripts for: convert CBR to CBZ across an entire library, convert PDF to CBZ, rename thousands of files to a consistent pattern, edit the pages inside a CBZ from the browser, write ComicInfo.xml metadata from Metron, ComicVine, GCD, AniList or MangaDex, and track weekly comic releases with a pull list. Everything happens through the web UI, so you can maintain a remote comic book collection without shell access to the server.

Documentation · Full feature list · FAQ · Discord · Docker Hub

Why CLU Exists

This started as a set of utilities built while moving a 70,000+ issue comic library to Komga. It has since grown into a stand-alone comic library manager: run it alongside Komga or Kavita as the maintenance and metadata layer, or run it on its own and read in the browser.

What CLU Does

• Convert CBR to CBZ in bulk — convert a folder, or an entire library, from RAR-based CBR to CBZ. Also converts PDF to CBZ with a JPEG or WebP output choice.
• Edit CBZ files in the browser — a full GUI editor: rename and drag-reorder pages, add or delete images, crop covers, split a multi-issue CBZ into single issues, combine files, enhance image contrast and brightness.
• Clean up and rename files — bulk rename with custom patterns, remove text from filenames, zero-pad issue numbers, strip junk files and __MACOSX folders, and run a missing-issue check against a series.
• Comic metadata editing — read and write ComicInfo.xml using Metron, ComicVine, Grand Comics Database, AniList, MangaDex, MangaUpdates and Bedetheque. Bulk tag a whole directory, review changes before they apply, and revert them from a history log.
• Source Wall — a spreadsheet-style view for reviewing and correcting metadata across many issues at once.
• Browse and read your collection — paginated library browsing, per-series pages, folder thumbnails, favorites, and a built-in page-by-page reader that remembers where you left off.
• Reading lists — import CBL files or story arcs from Metron and ComicVine, map entries to files you already own, and see what is missing.
• Pull list and weekly comic releases — subscribe to series, track new weekly releases, and keep a Wanted list of issues you do not have yet.
• Comic downloads — search and download from Direct Download Source, Usenet via Newznab indexers with SABnzbd or NZBGet, and DC++/AirDC++, with configurable source priority and a browser extension for one-click sends.
• Folder monitoring — watch a downloads folder and automatically unpack, convert to CBZ, rename and file new comics into your library.
• Insights, Timeline and CLU Wrapped — collection size and reading stats, a full timeline of what you have read, and shareable year-in-review images.
• Multi-user with per-folder permissions — Reader, Clerk and Store Owner roles, per-library and per-folder access grants, and per-user reading history. Single-user installs need no login at all.
• API and OPDS — a token-authenticated /api/v1 for companion apps, self-documenting at /api/v1/docs, plus OPDS feeds for comic reader apps and optional Komga reading sync.

See FEATURES.md for the complete breakdown.

Installation

CLU is distributed as a Docker image: allaboutduncan/comic-utils-web.

Quick start

docker run -d \
  --name clu \
  -p 5577:5577 \
  -v clu-config:/config \
  -v /path/to/cache:/cache \
  -v /path/to/comics:/data \
  allaboutduncan/comic-utils-web:latest

Then open http://localhost:5577.

Docker Compose (recommended)

Copy the following and edit the environment variables and volume paths.

services:
    comic-utils:
        image: allaboutduncan/comic-utils-web:latest

        container_name: clu
        logging:
            driver: "json-file"
            options:
                max-size: '20m'  # Reduce log size to 20MB
                max-file: '3'     # Keep only 3 rotated files
        restart: always
        ports:
            - '5577:5577'
        volumes:
            - 'config-volume:/config' # Maps to a Docker Volume for Database Storage and Backups
            - "/path/to/local/cache:/cache" # Maps to local folder for thumbnail cache
            ## update the line below to map to your library.
            ## Map your first/main library to /data
            - "/e/Comics:/data"
            ## Map additional libraries and add them in the settings of the app
            - "/e/Manga:/manga"
            - "/f/Magazines:/magazines"
            ## Additional folder if you want to use Folder Monitoring.
            - "/f/Downloads:/downloads"
        environment:
            - FLASK_ENV=production
            ## Set to 'yes' if you want to use folder monitoring.
            - MONITOR=yes/no
            ## Set the User ID (PUID) and Group ID (PGID) for the container.
            ## This is often needed to resolve permission issues, especially on systems like Unraid
            ## where a specific user/group owns the files.
            ## For Unraid, PUID is typically 99 (user 'nobody') and PGID is typically 100 (group 'users').
            ## For Windows/WSL, set these to match your Windows user ID (see docs/WINDOWS_WSL_SETUP.md)
            - PUID=99
            - PGID=100
            ## File creation mask. 000 -> world-writable folders (drwxrwsrwx) and files
            ## (-rw-rw-rw-). Use 002 for group-writable (775/664) or 022 for owner-only writes.
            - UMASK=000
volumes:
  config-volume: # Now required for Database Storage and Backups

Update your Docker Compose: Mapping the /config directory is required to ensure config settings and the database persist across updates.

First install: visit the config page and confirm everything is set up the way you want it, then:

• Save your Config settings
• Click the Restart App button

Windows and WSL users hitting file permission errors should read docs/WINDOWS_WSL_SETUP.md.

Mapping your library volumes

Map your main library to /data. Additional libraries can be mapped to any path and then added in the app's settings. Full install walkthrough: clucomics.org quickstart.

Integrations

Integration	What it is used for
Metron	Comic metadata, series, story arcs, weekly releases
ComicVine	Comic metadata via API, or a local offline database
Grand Comics Database	Optional local SQLite metadata database
INDUCKS	Optional local SQLite database of Disney comics worldwide
AniList / MangaDex / MangaUpdates	Manga metadata
Bedetheque	Bandes dessinées (European comics) metadata
Komga	Optional reading-history sync
Direct Download Source	Comic download search and grabbing
SABnzbd / NZBGet	Usenet download clients
Newznab indexers	Usenet search
AirDC++	DC++ download source
MEGA / Pixeldrain	Supported download mirrors
OpenAI / Anthropic / Gemini	Optional AI-powered reading recommendations
OPDS	Feeds for third-party comic reader apps

How CLU Compares

CLU is not a replacement for a comic server — it is the layer underneath one.

Tool	What it is for	With CLU
Komga / Kavita	Serving and reading your library	CLU maintains the files and metadata they read; CLU can also sync reading history from Komga
Mylar3	Comic downloading and series tracking	Overlapping — CLU covers pull list, wanted issues and downloads, plus file and metadata tools Mylar does not have
ComicTagger	Tagging individual comic files	CLU does bulk tagging across a whole library, with review and revert
CLU	Bulk file operations, CBZ editing, metadata, downloads, browsing and reading	—

Plenty of people run CLU and Komga against the same folders. That is the intended setup.

Frequently Asked Questions

How do I convert CBR to CBZ in bulk?

Point CLU at a directory and run Convert Directory, or run Convert Entire Library to CBZ to process everything at once. Conversion uses unar, so it handles RAR-based CBR files that many tools choke on. See Convert Directory.

Can I convert PDF to CBZ?

Yes. CLU converts PDF comics to CBZ and lets you choose JPEG or WebP for the extracted pages. See Convert PDF to CBZ.

Can CLU catch a wrong metadata match?

Optionally, yes. The metadata date check compares the matched issue's date against the year in the filename and flags a match that disagrees wildly — the case where the series matched is the wrong one and the issue number resolved anyway. Off by default, with a log-only mode so you can see what it would do before it does anything.

How do I find damaged comics?

The Problem Files page collects every file an operation could not read — a truncated download, a bad checksum, a RAR wearing a .cbz name — with the cause in plain English and the action most likely to help. It does not scan your library; a file appears because something tried to open it and failed. You can search your download sources for a replacement from the row, and CLU files it straight onto the damaged file, keeping the old copy in the Trash.

Does CLU edit ComicInfo.xml?

Yes — CLU is a full comic metadata editor. It reads and writes ComicInfo.xml, creates it when missing, and can bulk-update fields across an entire directory. Metadata can be pulled from Metron, ComicVine, GCD, AniList, MangaDex, MangaUpdates or Bedetheque, reviewed before it is applied, and reverted afterwards from the metadata history.

Does CLU work with Komga or Kavita?

Yes. CLU operates directly on the files on disk, so anything you fix or tag in CLU shows up in Komga or Kavita after a scan. CLU can also sync reading history from Komga.

Can multiple people use one CLU install?

Yes. CLU supports multiple accounts across three roles — Reader, Clerk and Store Owner — with per-library and per-folder access grants. Reading history, favorites and reading lists are kept separate per user. A single-user install requires no login at all.

Is there a mobile app or OPDS support?

CLU serves OPDS feeds that work with standard comic reader apps, and exposes a token-authenticated /api/v1 for companion apps, documented in-app at /api/v1/docs.

Can I read comics directly in CLU?

Yes. CLU has a built-in browser-based reader with page-by-page navigation that remembers your position, plus Continue Reading and On the Stack views.

Does CLU need an internet connection?

Only for metadata lookups, downloads and recommendations. All file operations — conversion, renaming, CBZ editing, browsing and reading — work entirely offline. GCD and ComicVine can also run from local databases.

Do I need shell access to my server to use CLU?

No — that is the point. Every operation runs through the web UI, so you can maintain a remote comic collection without SSH.

What file formats does CLU support?

CBZ, CBR, PDF, and the plain ZIP and RAR archives that comics are often distributed in. CBZ is the working format everything converts to.

Where is the full documentation?

At clucomics.org, including a setup walkthrough and a page for every feature.

Screenshots

Community & Contributing

• Discord — questions, support and feature discussion
• Documentation — full install and feature docs
• CONTRIBUTING.md — how to contribute code, including adding new metadata providers
• SECURITY.md — reporting a security issue
• CODE_OF_CONDUCT.md — community expectations
• Issues — bug reports and enhancement requests

License

Licensed under the GNU General Public License v3.0.

Say Thanks

If you enjoyed this, want to say thanks or want to encourage updates and enhancements, feel free to