Substring Extractor
Extract text by position and length. Supports multi-line mode, reverse extraction, and character counting. Free, private, runs in your browser.
How does substring extraction work?
Set the start position (1-based) and length. The tool extracts the matching portion of text and displays it as the result. For example, position 3 with length 4 from 'Hello World' returns 'llo '.
What is 1-based indexing?
Position 1 refers to the first character of the text. This is different from programming languages like JavaScript or Python that use 0-based indexing, where position 0 is the first character.
What is multi-line mode?
In multi-line mode, each line is processed independently. The same start position and length are applied to every line separately, making it ideal for batch extraction from structured data.
What is reverse extraction?
Reverse extraction counts positions from the end of the text. Position 1 is the last character, position 2 is the second-to-last, and so on. Useful when you need to extract from the tail of a string.
Is my data safe and private?
Yes. All processing happens locally in your browser. No data is uploaded to any server. Your text remains completely private and secure.
Does it count characters or bytes?
It counts characters, not bytes. This means Unicode characters like emojis (π), accented letters (Γ©), and CJK characters (δΈζ) are each counted as one character.
What happens if the position exceeds the text length?
If the start position is beyond the text length, the result will be empty. If the length extends beyond the text, only the available characters within range are extracted.
Can I extract from the end of text?
Yes. Enable reverse mode to count positions from the end. Position 1 in reverse mode is the last character of the text.
What are common use cases?
Common uses include extracting file extensions, parsing CSV columns, extracting domains from URLs, pulling specific fields from log entries, and processing structured text data.
Does this tool work offline?
Yes. Once the page is loaded, all processing is done locally in your browser. No internet connection is required for the extraction itself.
How to Use Substring Extractor
Pull out exactly the part of a text you need by position and length, with multi-line and reverse extraction supported. Everything happens locally in your browser and nothing is sent to a server.
- Paste your source text into the input box that says "Type or paste your text here...".
- Enter the starting position in the "Start (1-based):" field β the first character is position 1.
- Type how many characters to extract in the "Length:" field.
- Read the extracted fragment in the result box that says "Result will appear here...".
- Enable multi-line or reverse extraction when you need to keep line breaks or count from the end.
With "Start (1-based): 1" and "Length: 5" you get the first five characters, so mentally subtract 1 from where you want to begin.
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