Compress exports and restore the exact original data locally.
—Run the check to see a real result here.
Compression Streams
What this proves & next steps
Compresses repetitive generated text with gzip, decompresses it and compares the whole text. Savings depend on the data; photos and ZIPs may barely shrink.
If it doesn’t work: Use a compression library or offer uncompressed downloads.
Store structured projects on this device without a server account.
—Run the check to see a real result here.
IndexedDB
What this proves & next steps
Creates a uniquely named test database, commits a record, reads it in a new transaction and deletes the database. This does not guarantee long-term persistence.
If it doesn’t work: Keep a downloadable project backup. Browser settings, private mode and storage limits can prevent saving.
Create a checksum to catch changed or corrupted data.
—Run the check to see a real result here.
Web Crypto / SHA-256
What this proves & next steps
Hashes the standard “abc” sample and verifies all 256 bits against its known SHA-256 digest. This is an integrity primitive, not proof that a file is trustworthy.
If it doesn’t work: Use a maintained hashing library. Web Crypto may require a secure page context.
Let the browser ask you to select a serial device.
—A browser prompt opens only when you choose to test.
Web Serial
What this proves & next steps
Asks for a serial port and checks that a handle was returned. The port is never opened, read or written. A selected handle does not prove device communication.
If it doesn’t work: Use a native serial tool, or import a recorded trace. Hardware, browser support and site permissions all affect availability.
Download your results, or bring in a report from another browser to see what changed. Reports contain test outcomes, timing and page context. No file contents or device identifiers.
How to read this report
Verified means the stated operation completed and its output passed a check. Unavailable means the required API is missing. Blocked means browser policy or permission stopped it. A cancelled picker is recorded separately.
These are small functionality checks, not speed rankings, security audits or guarantees for an entire application. GPU compute does not prove that an AI model will fit. Temporary storage round trips do not prove durability or offline reload. Results apply to this page and this browser session; other sites may have different policies.
Each test links to its documentation. The result comes from your browser, not a hard-coded compatibility table. Automatic tests use generated data only. Serial selection never opens, reads or writes the port; file selection never reads your file.