What happens to headings when you merge
Heading levels from each file are preserved exactly as-is. The tool does not adjust or renumber headings automatically. If file A ends with an H2 and file B starts with an H1, that H1 stays as H1 in the merged output.
If you want consistent heading hierarchy across the merged document, you need to bump heading levels down in each file before merging. For example, if you're merging 4 chapter files and want them all under a master H1 title, turn all H1s into H2s in files 2, 3, and 4 before uploading them.
The tool adds a separator between files if you want one. Use --- for a horizontal rule, or a blank line for clean separation. You can also add file headers as Markdown headings to mark where each source file begins in the merged output.
This is the number one thing Markdown users worry about when merging. The tool does not try to be smart about headings because every use case is different. Some people want all chapters at the same level. Others want nested hierarchies. Manual control before merging gives you exactly what you need.
When to use this vs cat or pandoc
Use this tool for one-off merges with no setup. Upload files, click merge, download the result. No command line, no installation, no configuration files. If you need to merge Markdown files once or twice, this is the fastest way.
Use cat *.md > merged.md in the terminal if you're comfortable with the command line and want something repeatable. This works great for automated builds or documentation pipelines where you're merging the same files over and over. You can script it and run it in CI/CD.
Use pandoc if you need to convert the merged output to PDF, HTML, or DOCX at the same time. Pandoc can merge and convert in one step, and it handles complex formatting like citations, cross-references, and custom templates. But it requires installation and learning the command syntax.
The online tool is fastest for non-developers working with Markdown docs. No installation, no terminal commands, just drag and drop. For developers who merge files regularly, cat or a build script is more efficient.
Works with Obsidian, Notion exports, and GitHub docs
Obsidian exports are standard Markdown and work fine. Obsidian uses plain .md files with no special formatting, so they merge without issues. If you're using Obsidian for note-taking and want to combine notes into a single document, this tool handles it.
Notion exports include extra metadata lines at the top of each file. These look like property declarations or database fields. Remove those before merging if you don't want them in the output. They're not standard Markdown, so they'll show up as plain text in the merged file.
GitHub wiki and docs pages export as plain .md files that merge without issues. GitHub uses standard Markdown (with some extensions like task lists and tables), and all of that syntax is preserved during merging. Links and images work as long as the paths are still valid after merging.