Every credit-card number ends with a checksum digit produced by the Luhn algorithm. Confirming the sequence helps spot typos, reject forged data, and reduce chargeback risks across e-commerce. Identifying the issuer network further streamlines routing rules. Understanding these fundamentals empowers developers and support teams during payment-flow troubleshooting in production and test environments.
The browser-only validator parses pasted values, comma-separated lists, or uploaded text files, stripping whitespaces and symbols before running instantaneous checksum calculations. A reactive interface labels each number valid or invalid, maps Major Industry Identifier and Issuer Identification Number, and draws a donut chart summarising validation ratios. All logic executes locally, so no network calls occur, preserving confidentiality for development and auditing tasks.
Use the tool when populating test databases, verifying customer support screenshots, or cleaning analytics feeds before pipeline ingestion. Its bulk-processing capability removes thousands of incorrect numbers in seconds, saving gateway fees. Developers can also embed the formatted JSON output directly into automated regression tests. Avoid entering genuine production card numbers on shared machines or public demonstrations.
Technical Details:
This single-page utility mounts inside any modern browser. Pasted or imported data is normalised client-side, then passed through a checksum and pattern-matching engine. A lightweight charting layer renders the results in real time without additional downloads.
No requests leave the session: file handling, number parsing, validation, and visualisation run entirely within the execution context, meeting privacy-by-design requirements and easing security reviews.
Feature Breakdown
Bulk Validator
Enter or import unlimited numbers; the engine loops through each value, runs checksum logic, and returns pass-fail flags within milliseconds, even on modest hardware.
Card Scheme Detection
Regular-expression mapping reveals Visa, MasterCard, American Express, and niche issuers, helping compliance teams route transactions to appropriate acquirers with minimal false positives.
MII & IIN Insight
Display of Major Industry Identifier and Issuer Identification Number empowers analysts to check portfolio coverage and investigate suspicious allocations quickly.
Instant Donut Chart
A lightweight charting layer visualises valid versus invalid ratios, automatically resizing on window changes, aiding slide deck screenshots for stakeholder updates.
JSON Export
Copy or download prettified JSON summaries so automated pipelines or test suites can reuse the same evaluation results without reprocessing raw lists.
Drag-and-Drop Import
Drag plain-text or CSV files onto the textarea to trigger automatic parsing and validation, eliminating manual copy-paste loops during quality-assurance tasks.
Calculations & Scoring:
The validator applies the Luhn algorithm to every digit sequence, classifying outputs as Valid or Invalid and tallying ratios for graphical display.
Formula
Reverse digits → 79927398713
Double every 2nd digit → 7 18 9 14 7 18 9 16 7 2 6
Subtract 9 when >9 → 7 9 9 5 7 9 9 7 7 2 6
Sum results → 76
Valid if sum % 10 == 0 → 76 % 10 = 6 ❌
Example
| Number | Checksum | Result |
|---|---|---|
| 4539 1488 0343 6467 | 7 | Valid |
| 6011 1111 1111 1117 | 7 | Invalid |
Data Privacy: Checks run locally; no card data is transmitted or stored.
Step-by-Step Guide:
Follow these quick steps to validate your list.
- Paste numbers into Credit-card numbers textarea or Import List from file.
- Select Validate to run the checksum and open the Validation Summary.
- Switch between List, Stats, or JSON tabs to review details.
- Copy or download results via the buttons inside the JSON tab.
- (Optional) Toggle Advanced to drag-and-drop alternative files.
FAQ:
Common questions about functionality and privacy.
Is my data stored?
No. Processing happens entirely in your browser; nothing is sent to any server.
Which card types work?
The tool recognises all major networks plus several niche issuers through pattern matching.
Unknown issuer shown?
The prefix may belong to an unlisted or private-label scheme; validation remains accurate.
Large file limits?
Modern browsers comfortably handle tens of thousands of lines; performance depends on device memory.
Accuracy of results?
The checksum implementation follows ISO 7812 rules exactly; additional scheme detection uses tested patterns.
Troubleshooting:
Resolve common issues encountered during validation.
- Textarea stays blank – ensure clipboard permissions allow pasting.
- All numbers marked Invalid – confirm they contain only digits; remove formatting characters like “–”.
- Chart not showing – open the Stats tab after at least one validation run.
- Copy JSON button unresponsive – browser may block clipboard access; use the download option instead.
- Drag-and-drop fails – verify file extension is .txt or .csv and below 5 MB.