Check whether a form accepts a file just below the limit and rejects one just above it. Exact byte counts make boundary testing easier.
Browser-based test data tools
Generate test files. Upload nothing.
Create files with an exact size, realistic CSV rows, structured JSON objects and downloadable text. Every generator runs locally in your browser, so you can move from an idea to a test fixture without accounts, packages or server processing.
No uploads, accounts or server-side file creation
testload://local
processingin browser
uploads0 bytes
account requiredfalse
outputready to download
Generators
Useful files for real testing
Each tool solves one common testing problem. Configure the output, inspect the preview where available, and download the result directly from the browser.
File Size Generator
Create a dummy file with an exact byte size using zero bytes, random bytes, repeating text or JSON-like lines.
Open generator →Sample CSV Generator
Generate up to 100,000 fictional records with configurable delimiters, quoting, headers and line endings.
Open generator →Sample JSON Generator
Create valid arrays or wrapped object collections with deterministic data and compact or readable formatting.
Open generator →Text to File
Paste text and save it as TXT, Markdown, HTML, CSS, JavaScript, JSON, XML or CSV with selected line endings.
Open generator →Use cases
What can you test with generated files?
TestLoad is intended for ordinary development and quality-assurance work where the content itself matters less than the size, format or predictable structure of the fixture.
Use larger files to observe progress bars, cancel controls, retry behavior and messages shown during slow operations.
Exercise delimiter detection, header mapping, row validation, encoding assumptions and handling of many records.
Test array and object-root payloads, compact output, pretty output and front-end rendering with repeatable records.
Create LF and CRLF fixtures to verify software that processes files from different operating systems.
Compare plain UTF-8 text with BOM-prefixed files in spreadsheet tools, importers and older applications.
Workflow
Three steps from settings to file
01 / SELECTChoose a generator
Pick the file type that matches the upload, import or processing flow you need to verify.
02 / CONFIGURESet useful constraints
Control size, row count, output shape, delimiter, formatting, line endings and a repeatable seed.
03 / DOWNLOADGenerate locally
The browser creates the file and starts the download without transmitting the generated content to TestLoad.
Local processing
Why generate test files in the browser?
Less setup for temporary fixtures
A test file is often needed for a few minutes: to reproduce a bug, confirm a validation rule or demonstrate an import workflow. Installing a package or writing a one-off script can take longer than the test itself. TestLoad keeps those small tasks in a focused interface.
The output is built with browser APIs such as Blob, TextEncoder and object URLs. After the file is created, the browser handles the download in the same way it handles a file produced by another web application.
Inputs remain on the device
The generators do not need to upload pasted text or generated datasets. This reduces unnecessary data transfer and makes the tools useful for non-sensitive fixtures even when you do not want the content processed by a remote service.
Local processing does not remove normal browser limits. Very large files can consume significant memory, especially on mobile devices, so TestLoad applies practical maximum sizes and clearly reports them in each tool.
Technical notes
Small details that change test results
File testing is often about details that look interchangeable until an importer, validator or operating system treats them differently.
| Option | What it changes | Typical reason to test it |
|---|---|---|
| MB vs MiB | 1 MB is 1,000,000 bytes; 1 MiB is 1,048,576 bytes. | Confirm which unit an upload limit actually uses. |
| LF vs CRLF | Text lines end with one byte or two bytes. | Verify cross-platform text import behavior. |
| CSV delimiter | Fields are separated by comma, semicolon, tab or pipe. | Check locale-specific spreadsheet and importer settings. |
| Compact JSON | Optional whitespace is removed. | Compare payload size and parser behavior. |
| UTF-8 BOM | Three identifying bytes are added to the beginning of the file. | Test older software and spreadsheet encoding detection. |
| Random seed | The same pseudo-random sequence can be reproduced. | Repeat a failed test with identical fixture values. |
FAQ
Common questions
Are generated files uploaded to a server?
No. File creation happens in your browser with standard web APIs. Generator settings and generated content are not sent to TestLoad.
Can TestLoad create an exact file size?
Yes. The file size generator creates the exact number of bytes requested. You can choose decimal KB and MB or binary KiB and MiB units.
Why is the largest file limited to 512 MiB?
Browser memory varies by device and tab. The limit reduces the chance of freezing a browser or exhausting memory, particularly on phones and older computers.
Can I reproduce the same sample data?
Yes. The CSV and JSON generators use a numeric seed. The same settings and seed produce the same values in the same order.
Are generated names and email addresses real?
No. Sample records are fictional and use example-style domains. They are intended only for development and testing.
Does changing a file extension convert the content?
No. The Text to File tool saves the text you provide. Choosing .json or .html sets the file name and media type but does not validate or rewrite the syntax.