Any format. Any size. No wait.
Generate a test file at the size you need
Choose a format and a byte size, then generate and download a test file in your browser. Use previews and format notes to check what each fixture can test.
1 MB = 1,000,000 B · 1 MiB = 1,048,576 B
Advanced: test an upload limit
Enter the byte limit above, then choose one byte below, the exact limit or one byte above. Each choice uses the same base: 10,485,760 B. Generate and download each file to test your endpoint.
Popular tools.
Jump straight to the tools people reach for first.
Free file tools.
ByteRivet is also a full toolkit for files you already have — merge, convert and edit PDFs and images, free and without installing anything.
The file never travels.
Other generators keep a folder of pre-made files and hand you a link. That means fixed sizes and a wait proportional to your connection. Here the bytes are written where you already are.
- Runs locally
- No upload
- No account
- Exact byte sizes
Pick a family.
Every format has its own page with common sizes, structural notes and what the padding contains.
Documents
Paper-shaped files for upload forms and print pipelines. Download DOCX, HTML, MD, PDF and TXT files at an exact size — no upload, no signup.
- DOCX
- TXT
- MD
- HTML
Images
Raster and vector, sized for avatar and gallery limits. Download JPG, PNG, SVG and WebP files at an exact size — no upload, no signup.
- PNG
- JPG
- WebP
- SVG
Data
Tables and payloads for import limits and API body caps. Download CSV, JSON, SQL, XLSX and XML files at an exact size — no upload, no signup.
- CSV
- JSON
- XLSX
- XML
- SQL
Media
Audio and video containers for ingestion queues. Download MP3, MP4 and WAV files at an exact size — no upload, no signup.
- WAV
- MP3
- MP4
Archives
Packages and raw bytes for throughput tests. Download BIN and ZIP files at an exact size — no upload, no signup.
- ZIP
- BIN
System
Executables, scripts and disc images for platform and upload testing. Download BAT, EXE and ISO files at an exact size — no upload, no signup.
- EXE
- BAT
- ISO
Where the bytes go.
Exact size comes from format-specific structures, comments, extra parts or trailing data. Reader support and re-saving behavior vary; use these fixtures to test your actual application.
| Format | Padding region | Opens in | Minimum |
|---|---|---|---|
| BIN | The entire file is pseudo-random printable bytes | hex editors like HxD or xxd, and Python's open() in binary mode | 1 B |
| ZIP | A payload file stored inside the archive without compression | Explorer, Finder, 7-Zip and unzip | 368 B |
| CSV | Additional rows, with the final row padded to land on the exact byte | Excel, Sheets, pandas and Python's csv module | 80 B |
| JSON | A trailing string field, so the document still parses | jq, browser devtools, Python's json module and Node's JSON.parse | 60 B |
| An unreferenced content stream, the same mechanism PDF writers use for incremental updates | Acrobat, Preview, Chrome, pdf.js and pypdf | 772 B | |
| DOCX | A binary part declared in [Content_Types].xml, which Word ignores | Microsoft Word, LibreOffice, Google Docs and python-docx | 1,496 B |
Questions
What is ByteRivet?
A browser-based toolkit for files: an exact-size test file generator, plus PDF tools, image tools and format converters. Every tool is free, works without an account, and most of them never send your file anywhere.
Which tools run entirely in my browser?
The test file generator, PDF editing tools and image tools process your files locally using Web Workers. Your files are not uploaded. The page and required tool modules must load before processing can start.
Which operations use a server?
Office-to-PDF and PDF-to-Office use our server conversion engine. Files are sent over HTTPS; source deletion is attempted after processing, and results are deleted after download or by queue cleanup after their 15-minute lifetime. See Security for job metadata retention.
Is ByteRivet free?
Yes. No account or subscription is required. The test generator accepts up to 2 GiB; device memory and tool-specific limits still apply.
Which formats are supported?
The test file generator covers 22 formats, including PDF, PNG, JPG, WebP, ZIP, DOCX, XLSX, CSV, JSON, XML, HTML, SQL, MD, SVG, WAV, MP3, MP4, BIN, EXE, BAT, ISO and TXT. Format pages explain what each fixture contains and what it can test.
Does ByteRivet work on mobile?
Yes, every tool is responsive and works in a mobile browser. Browser-based tools are limited by your device's available memory, so very large files can be slower on a phone than a desktop.
Does 1 MB mean 1,000,000 bytes?
Yes: 1 MB is 1,000,000 bytes, while 1 MiB is 1,048,576 bytes. Choose MB or MiB in the unit selector. Historical size URLs such as /10mb/ keep their original binary byte count; the readout always shows the exact number.
Can I use the generated files in an automated test suite?
Yes. Generate and save a fixture for your suite, or automate the browser with Playwright. Image generation uses browser canvas APIs, so these generators cannot all run directly in plain Node.js.
Blog
Everything we measure, we write down.
We publish plain, technical, and practical content about file formats, upload limits, and conversion technologies.
View all posts →
How to Test File Upload Limits: A Practical Guide
Testing an upload limit properly means three exact files, not one: at the limit, one byte over, and comfortably under — here's how and why.
EXE Test Files: PE Headers and Upload Rules
Check extension, MIME and upload rules with a PE-header fixture. Learn what its zero PE sections and legacy DOS stub mean, and when a working program is needed.
File Upload Limits: Check Your Platform and Account
Find the official limit for your account and upload method, choose MB or MiB correctly, and verify the accepted byte size with boundary tests.
How to Create a Test File of Any Size
Learn how to create exact-size test files for upload limits, API testing, email attachments, storage checks and QA workflows.