Five Local Docker Tools for Safer Developer Workflows
IT-Tools, CyberChef, ConvertX, Hoppscotch CE and Kroki handle recurring developer tasks locally, with setup and data-handling tradeoffs.
A developer needs to decode a token, unpack a compressed log field or convert a screenshot. A public utility site may be the quickest option, but it means sending internal data to a service outside the project. Five small Docker services offer a practical alternative: inspect, transform, convert, test and diagram files on a machine you control. They’re useful precisely because they handle mundane work, though each brings its own setup and data-handling considerations.
These tools cover different jobs. IT-Tools gathers common inspection utilities in one interface; CyberChef chains data transformations; ConvertX wraps many file converters; Hoppscotch CE provides a persistent API workspace; and Kroki renders diagrams from text. Teams can start with the ones that match repeated tasks and add the others as their needs grow.
| Container | Use it for | Local advantage | First caution |
|---|---|---|---|
| IT-Tools | JSON, JWT, Base64, hashes, UUIDs, regex and cron | One local app replaces a trail of utility tabs | It’s a convenience layer, not a secret store or test suite |
| CyberChef | Chained decoding, decompression, hashing and re-encoding | Recipes make repeatable transformations easy to share | Decoding bytes doesn’t verify their contents |
| ConvertX | Images, documents, e-books, SVG, video and more than 1,000 formats | Files stay on the machine; accounts and automatic cleanup are included | Untrusted files remain untrusted; claim the first account promptly |
| Hoppscotch CE | Requests, collections, environments and request history | The workspace can live alongside a project | It needs several services and Postgres; its environment file and history can contain secrets |
| Kroki | PlantUML, GraphViz, D2, Structurizr and other diagram syntaxes | Text diagrams render locally without a hosted service | Add companion images only for syntaxes the project uses |
IT-Tools: A single place for small checks
IT-Tools brings together common developer utilities: JSON formatting and comparison, JWT decoding, Base64 encoding and decoding, hash generation, UUID creation, regex testing, cron helpers, and color and date conversion. Its Docker setup is a single command:
docker run -d --name it-tools --restart unless-stopped -p 8080:80 corentinth/it-tools:latestVisit localhost:8080 to use the app locally. The gain is convenience: a developer can keep recurring checks in one place instead of searching for a different utility each time. That doesn’t make IT-Tools a secure vault. Treat pasted material with care, and remember that decoding a JWT reveals its contents but doesn’t establish whether a server will accept it.
CyberChef: Repeatable transformations for opaque data
When data has several layers of encoding or compression, running operations one by one can be tedious and error-prone. CyberChef, built by GCHQ, lets users assemble a sequence of operations into a recipe. Its ready-to-run image, ghcr.io/gchq/cyberchef:latest, serves the app on port 8080.
A recipe might convert input from hex, decompress it with Gunzip, decode the resulting text as UTF-16, then format it as JSON. CyberChef can rerun that sequence as the input changes; users can save recipes, reload them or share them by URL. Breakpoints help inspect intermediate results, while the Magic operation can suggest likely decoding steps when the format is unclear. The app runs client-side, so the container doesn’t need a backend.
That makes local use appealing for internal tokens, customer files or incident data. But a successful decode only shows what the bytes contain. It doesn’t establish that the contents are accurate, complete or safe to act on.
ConvertX: A local front end for many file formats
ConvertX provides one upload interface for conversion tools such as FFmpeg, ImageMagick, LibreOffice, Pandoc, Calibre and Inkscape. Its README lists support for more than 1,000 formats. The documented Compose deployment uses the ghcr.io/c4illin/convertx image on port 3000, a JWT_SECRET value and a local folder mounted at /app/data. That mount preserves uploads and converted files when the service restarts.
Accounts and password protection are included, as is a cleanup job that removes converted files after 24 hours by default. Common jobs include turning a HEIC screenshot into a PNG, converting a DOCX file to Markdown, or changing a screen recording into a format a ticketing system accepts. With ConvertX running locally, those files don’t need to leave the machine for conversion.
Local hosting doesn’t make file parsing risk-free. Keep the service on localhost or protect it with authentication. The README also warns that the first person to reach the page can register the initial account, so create it right away and leave ACCOUNT_REGISTRATION off, as it is by default.
Hoppscotch CE: An API workspace with a heavier setup
Hoppscotch stores requests, collections, environments, variables and request history between sessions. A hosted app may suit a one-off call; a local Community Edition workspace can make more sense when a team repeatedly tests the same API and wants its collections and environments near the project.
Expect more setup than with the other tools. Hoppscotch CE needs a Postgres database and can run as three services—the frontend on port 3000, backend on 3170 and admin interface on 3100—or as an all-in-one image. Before launch, configure a .env file with the DATABASE_URL, a 32-character DATA_ENCRYPTION_KEY and the origins permitted to connect. The first login depends on running the Prisma migration against the database.
That’s a meaningful stack for a developer utility. If API testing is occasional, a hosted tool or curl may be simpler. If the same API gets exercised regularly, a persistent workspace can justify the extra work. In either case, the environment file and request history may contain credentials and internal hostnames, so handle them like project secrets.
Kroki: Diagrams generated from text
Kroki accepts diagram source over HTTP and returns a rendered image, such as SVG. Its gateway supports PlantUML and Graphviz, along with D2, Structurizr, Ditaa and about twenty other syntaxes. The yuzutech/kroki image runs on port 8000 and includes many renderers. Mermaid, BPMN, Excalidraw and diagrams.net require companion containers.
This setup supports diagrams as code: keep a .puml file beside source code, review changes alongside other project work and regenerate the diagram when the system changes. Start with the gateway and add companion images only if the project needs their formats. Each additional image adds another component to maintain.
Build a small stack around repeated work
These five tools cover inspection, transformation, conversion, API testing and diagram rendering. Start with IT-Tools and whichever of CyberChef or ConvertX addresses a task that comes up regularly. Add Hoppscotch when API work becomes routine, or Kroki when diagrams need ongoing updates.
When services need to communicate, Docker Compose can put them on a shared default network, where one service can reach another by its name. For example, a container can call http://kroki:8000. Named volumes can preserve ConvertX’s data and Hoppscotch’s database between runs.
Pin image tags for services a team depends on, and stop containers that are no longer in use. Keep the services off the public internet unless they’ve been deliberately secured. For further configuration guidance, see KDnuggets’ article on practical Docker configurations.
A local utility won’t remove every reason to use a web tool, but it gives developers a straightforward option for recurring jobs involving project data. The best starting point is the container that replaces a task you already do every week.
