Join text files

Combine ordered text, CSV, TSV, JSONL, Markdown or log files into one UTF-8 text file without uploading their contents.

Drop files here or choose themProcessed locally in your browser when supported.

What this tool actually does

Join text files parses the content as structured data or text before generating the output. JSON, XML, CSV, TSV, Markdown and damaged text are not treated as arbitrary strings where changing a filename would be enough.

How the result is verified

Whenever the format allows it, the generated result is parsed or validated again. Quoted fields, delimiters, XML/JSON structure and text encoding are handled with format-specific checks to reduce outputs that look plausible but cannot be read correctly by the next application.

Limits and fidelity

Limits protect the browser from disproportionate files, rows, columns or cell sizes. The conversion preserves information the destination can represent but does not invent types, relationships or meaning missing from the source. Review critical datasets before replacing the original.

When to use this workflow

Use this workflow when a system requires another representation of the same data, when syntax needs validation or when text displays broken characters. For legal, financial or production-critical information, keep the original and compare a representative sample before relying on the transformed file.

Privacy and final verification

Keep the original file until the output has been reviewed in the destination application or portal. Supported workflows process locally in the browser and enforce bounded size and complexity limits. For Join text files, verify that the generated format preserves the properties that matter for your use case. For important data, compare a representative sample and confirm that format, content and quality meet the actual requirement before replacing the source file. Also open the generated file in the destination application when compatibility, colour, transparency, layout or compression matters.

Combine log files without changing existing lines

Select 2–100 UTF-8 text, Markdown, JSONL, CSV, TSV or log files in the intended order. The output is one TXT file. Existing bytes, whitespace and line endings are retained; only one LF is inserted at a boundary where the previous file has no final line break. For example, joining error-01.log and error-02.log preserves their original records without merging the last and first lines.

Not a CSV or TSV table merge

The tool concatenates text; it does not compare column names, deduplicate CSV headers or reconcile different delimiters. If two CSV files each contain a header, both headers remain in the result. Use CSV to TSV for delimiter conversion or split text files to create numbered byte-exact parts.

Safety limits and encoding checks

Input is limited to 20 MiB per file and 40 MiB combined. Every file must be valid UTF-8 without NUL bytes; a BOM is permitted only at the start of the first file. All sizes are checked before reading content. Cancellation is checked between file reads and before producing a download, but cannot instantly interrupt a file read already in progress.

When to repair encoding first

For legacy encodings or corrupted characters, use repair text encoding before joining. Do not assume that concatenating JSONL logs will validate each JSON object: this tool preserves text, not a structured-data schema.