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PatternBenchBY SMARTFACT

FREE JAVASCRIPT REGEX WORKBENCH

Extract regex capture groups as JSON

Updated

Regex extraction collects the parts of text selected by a regular-expression match. PatternBench can export a chosen named capture as a JSON array of strings, preserving leading zeroes.

Free to use. No account, email address or trial. Your work stays in your browser.

The named number capture selected for extraction.
Extract the required part while retaining leading zeroes as text.

Run the capture pattern first

Supply a JavaScript pattern and source text, then check the completed matches. Extraction reads that match set rather than running a second different pattern. This exports captured strings as JSON; it is not a general JSON parser.

Completed matches ready for capture extraction.
Check the match set before choosing an export.

Choose the required capture

Open extraction and select the named number group. Choose the whole match or another supported capture only when it is the value you need. Empty or unexpected output calls for checking the actual pattern and input.

Only the number group selected in the extraction controls.
The exported value can be narrower than the complete match.

Export JSON strings

Choose JSON and download the result. Captured digits remain strings, so 0201 retains its leading zero. The download is an explicit local file and can outlive the tab.

Selected captures displayed as JSON strings.
JSON strings preserve the text rather than silently converting it to numbers.

Know the bounded match set

The workbench limits runs to 1,000 matches, 64 capture groups and 200,000 retained text/output code units. The table previews 100 rows; that preview is not the whole export. No document upload, PDF parsing or automatic expression repair is offered.

MADE FOR DEVELOPERS AND INTEGRATORS

For developers, integrators and people checking exact values before using them in another system.

A USEFUL STARTING POINT

Take only the part you need

A full reference may contain more than the receiving tool needs. Select one capture after checking the matches, retaining the original text representation of its digits.

FROM QUESTION TO EVIDENCE

Three steps to a useful result.

  1. 01

    Match

    Run the pattern against the exact source.

  2. 02

    Select

    Choose the named capture you need.

  3. 03

    Export

    Choose JSON and download the captured strings.

A CONCRETE EXAMPLE

A code keeps its leading zero

A captured value of 0201 is exported as the JSON string "0201", rather than the number 201. The source text is unchanged.

WHEN CHECKS REPEAT

From a useful check to everyday work.

These SmartFACT services handle work that repeats across a team or on each job. The workbench remains free and independent.

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LabelRules

When label checks must repeat for each job, LabelRules turns requirements described in plain English into approved selection and value-check rules. It starts with an invited trial. PatternBench does not publish rules into it.

Early access

KitProof

When expected components depend on order data, KitProof builds checklists from approved plain English rules and checks each scan against them. It is in early access, with scope agreed at onboarding.

BEFORE YOU START

A few practical answers.

Does this extract fields from arbitrary JSON?

This workflow exports regex capture values as JSON. Use a proper JSON parser when interpreting JSON structure.

Are leading zeroes retained?

Yes. Captured values are exported as strings.

Does extraction alter the source?

No.

Where is the file kept?

In your chosen local download location. Closing the tab does not remove that file.

What are the current limits?

Patterns and replacement text are limited to 4,096 UTF-16 code units each; samples to 100,000. Up to 1,000 matches and 64 capture groups are supported, with 200,000 retained text/output code units. Cases are limited to 50 values of 2,000 code units each. Highlighted preview shows 6,000 sample code units and the table 100 matches; complete results are used for replacement and export. The engine is the current browser’s JavaScript RegExp, not PCRE, .NET or another dialect. Matching a shape does not prove that a real-world value exists. Syntax explanations show up to 512 elements. Project files are limited to 1.5 MB. Generated snippets do not include the workbench’s worker or result limits.

What happens to my data?

Patterns, sample text, replacement text, cases and results stay in this tab’s memory. Workers run on this device and are discarded after completion, edits, cancellation or the execution limit. Nothing is uploaded, put in a page address or saved automatically. Refreshing or closing the tab discards the work. Clipboard copies, extraction exports, generated code and project files can contain your actual values. Opening a project reads the selected file locally and replaces the workbench only after validation. The tool has no analytics; these public pages offer optional suite analytics separately.

ONE SMALL JOB, DONE WELL

Put PatternBench to work.

Open the free tool and start with one known example.

Extract captured values →

THE SMARTFACT SUITE

Practical tools. Useful on their own.
Better around the same floor.

Automate factory decisions with rules you describe in plain English. Explore focused SmartFACT services, plus free tools for everyday checks.

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CheckStation

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OffcutBench

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Track offcuts free ↗
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TraceBench

Load one or two CSV exports and follow a lot or serial forwards or backwards, with the row behind every link. No account needed.

Start a free trace ↗
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Record the parts recovered from each return, label them with a QR code, check them and record the unit each one goes into. No account needed.

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Step-by-step guides and interactive demonstrations for the SmartFACT suite. Read the instructions, watch a task or practise with real product screens and sample data.

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