Merge multiple Fixed-Width Text files into one YAML

Why Choose Withdata DataFileConverter as a Fixed-Width Text Merger?

Full Feature Comparison

Fixed-Width Text to YAML — What Changes

The column names you defined become YAML keys. Because the columns are read positionally, a line that is shorter than the declared widths can shift the values that follow it.

All Fixed-Width Text Merge Options You Need

• Merge several Fixed-Width Text files into one YAML file — step by step in the GUI wizard
• Merge a whole folder of Fixed-Width Text files in one run
• Map the columns of each input file to the output columns
• Run the merge from the command line, and schedule it as a scheduled task
• All Fixed-Width Text tools and all YAML tools

Same source format, other targets

This page merges Fixed-Width Text into another format. If you need a different output, these pages each do that one job:

• Merge multiple Fixed-Width Text files into one Fixed-Width Text file
• Merge multiple Fixed-Width Text files into one CSV file
• Merge multiple Fixed-Width Text files into one TSV file
• Merge multiple Fixed-Width Text files into one TXT file
• Merge multiple Fixed-Width Text files into one Excel file
• Merge multiple Fixed-Width Text files into one JSON file
• Merge multiple Fixed-Width Text files into one XML file
• Merge multiple Fixed-Width Text files into one HTML file
• Merge multiple Fixed-Width Text files into one SQL file
• Merge multiple Fixed-Width Text files into one YAML file

All merge tools, by format

Merging into YAML — Notes

• Each merged row is written as one mapping in a top-level YAML sequence.
• The output indent is 2 spaces by default and can be changed; flow style ({ } / [ ]) can be toggled.
• Column names that contain dots (for example address.city) can be written back as nested mappings.
• When reading YAML: a top-level sequence of mappings is one row per mapping, nested mappings become dotted column names, and anchors/aliases/tags/multi-document files are not supported.
• There is no delimiter and no quoting — every column has a fixed width.
• Merged output widths are measured from the data (widest value plus 15% slack, at least 2 and at most 15 extra characters) and can be edited.
• For N columns, N-1 widths are used — the last column takes the rest of the line.
• When reading fixed-width files: N columns need N-1 widths, no delimiter is used, and the header row is optional.

How to Merge Fixed-Width Text Files (4 Steps)

1. Open Withdata DataFileConverter and choose Merge (combine multiple files into one).
2. Add the Fixed-Width Text files you want to merge — two files, a list, or a whole folder.
3. Check the preview and map the source columns to the output columns; then set the output options (Indent (2 spaces by default), flow style, nested mappings).
4. Click Convert — the single YAML file is written in seconds. Save the session if you want to run it again from the command line.

Start Merging Fixed-Width Text Files Today

Download Withdata DataFileConverter for a free trial. Runs on Windows, macOS and Linux.

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