WDL to PDF Converter – View, Copy, and Export Workflow Description Language Files Online

WDL File Viewer and PDF Export

This viewer opens WDL (Workflow Description Language) files in your browser with syntax highlighting, line numbers and a clickable outline of every workflow, task, call and runtime setting. Use it to review a pipeline without installing Cromwell, miniwdl or an IDE plugin. You can also copy the text, save it as a plain TXT file, or export a clean, printable PDF to share or archive.

How to Open and View a WDL File

1. Click Open file or drag a .wdl file onto the viewer. You can also click Edit / paste and paste WDL text directly.
2. Read the highlighted source on the right. Turn line numbers and line wrapping on or off to suit the file.
3. Use the Outline to jump straight to a workflow input, a call, a task's command section or its runtime settings.
4. Click Copy, Download TXT or Export PDF when you're done.

What Is a WDL File?

A .wdl file is a plain-text workflow written in the Workflow Description Language, an open standard created at the Broad Institute and maintained by the OpenWDL community. It is widely used in genomics and bioinformatics to describe multi-step pipelines, such as aligning sequencing reads and calling variants, so they can run the same way on a laptop, an HPC cluster or a cloud platform like Terra.

A WDL file is built from a few main parts:

• version – the WDL version the file follows, such as version 1.0 or version 1.1. Files without one are treated as the older draft-2 format.
• workflow – the pipeline itself, with its inputs, outputs and the call statements that run tasks, often inside scatter loops or if blocks.
• task – a single step, with its input, the shell command to run, its output files and values, and runtime settings such as the Docker image, CPU and memory.
• struct – a custom data type that groups related fields, such as a sample's name and FASTQ files.
• import – pulls tasks and workflows in from other WDL files under a namespace alias.

Viewer Features

Syntax Highlighting

Keywords, types, strings, numbers, comments and runtime keys are each shown in a different color. Inside command sections, the shell script is shown separately from WDL placeholders such as ~{threads} and ${reference}, so it's easy to see which values come from the workflow. Both command <<< >>> and command { } styles are supported.

Clickable Outline

The outline lists each workflow's inputs, steps and outputs, and each task's inputs, command, outputs and runtime settings. Calls inside scatter and if blocks are indented to show nesting, and aliased calls show both names, as in call CallVariants as call_variants. Click any entry to jump to that line.

Basic Checks

The viewer flags common problems that are easy to miss when reading by eye: unterminated strings, a command section with no closing >>> or }, unbalanced braces, calls to a task that isn't defined in the file, and tasks defined twice. Problem lines are tinted red and listed under the viewer with links to each one.

These are quick sanity checks, not full validation. To check that a workflow is valid before running it, use a dedicated tool such as womtool validate or miniwdl check.

Edit and Paste

Switch to Edit / paste to paste a workflow from a repository or an email, or to make a quick change before exporting. The outline updates as you type. Click Done editing to return to the highlighted view.

Exporting a WDL File to PDF

Export PDF creates a print-ready copy of the file with the file name, WDL version, line count and export date at the top, followed by the highlighted source. Long lines wrap so nothing is cut off at the page edge, and line numbers are included when they're turned on in the viewer. Your browser's print dialog opens. Choose Save as PDF as the destination to save the file.

A PDF copy is useful for attaching a pipeline to a methods section, a lab notebook or a review packet, or for keeping a fixed record of the exact workflow used for an analysis.

Downloading as TXT

Download TXT saves the exact contents as a .txt file, which opens anywhere without special software. This is handy when an email filter or upload form blocks the .wdl extension.

Common Questions

How do I open a .wdl file?

A WDL file is plain text, so any text editor can open it. This viewer adds highlighting, an outline and PDF export without installing anything. For editing larger projects, code editors like VS Code have WDL extensions.

Does this tool run my workflow?

No. It only displays the file. To run a WDL workflow you need an execution engine such as Cromwell, miniwdl, Sprocket or a platform like Terra.

Which WDL versions are supported?

The viewer highlights and outlines draft-2, 1.0, 1.1 and 1.2 files. The version shown in the file details comes from the file's version line.

Is my file uploaded?

No. The file is read and displayed in your browser, and copying, downloading and PDF export all happen on your device.