Learning & reference
Create test files from the command line
Copy-paste commands to make test files on Windows, macOS and Linux: a large file of an exact size, random data, N lines, a CSV, thousands of files at once, unique content per file, and how to generate & verify checksums. Hit Explain on any command to see what each part does. No install needed for our on-demand generator.
No terminal handy? The HEXAQA generator streams a file of any size, shape or type (CSV, JSON, XML, SQL, ZIP, UUIDs, binary) straight from your browser: nothing to install.
More from Learning
Guides and references for test data, file handling and AI evals. All free, no sign-up. See the full hub.
Synthetic data for AI evalsWhat you can download, what you buildRAG test corpusDocuments with extraction trapsJSONL for evalsThe format, and ten ways it breaksMock API for agentsRecords, pagination, failures on demandSafe test dataReserved domains, IPs, numbers & cardsSynthetic PIIFake people that reach nobodyTest card numbersEvery brand, declines, 3D SecureTest phone numbersReserved US, UK and Australian rangesReserved IP addressesDocumentation ranges and SSRF casesExample domains.test, .invalid, example.com, and trapsQA test stringsUnicode, emoji, injection & edge casesFilename compatibilityWhat breaks across Windows, Mac & LinuxFile systemsPOSIX, NTFS, APFS, ext4, SMB, NFS, NASFile signaturesMagic numbers that identify every formatCharacter encodingsUTF-8, UTF-16, BOM & normalizationUpload validationThe checklist, with a file for each checkMIME typesThe right Content-Type for every extensionHTTP status codesEvery code and when you actually see itDates & timesISO 8601, epoch, Excel serials, DSTHTTP headersContent-Type, Disposition, Range, CORSRegex cheat sheetSyntax, flags and ready-made patternsCrypto & certificatesSSL/PEM, hashing, encryptionWeb app testingWhat to test, with a file for each caseDesktop app testingPaths, names, encodings and savingMobile app testingPickers, photos, flaky networksCLI testingArguments, pipes and exit codesLarge file upload testingDefault limits, 413s and exact sizes1 GB test file1 GB and 2 GB, with SHA-25610 GB test fileMake one locally in secondsDownload speed test files10 MB to 2 GB of random data