What is checked
The inspector verifies the v3 length and Base32 alphabet, decodes exactly 35 bytes, requires version 0x03, and compares the embedded two-byte checksum with a local SHA3-256 calculation.
Tools · Privacy-first
Onion v3 Inspector
Validate the structure of a Tor Onion Service v3 address and inspect the identity data encoded inside it. The tool checks the 56-character Base32 service ID, decodes the 32-byte Ed25519 public key, verifies version 0x03, and recalculates the embedded SHA3-256 checksum.
It does not connect to Tor or the Onion Service. A valid checksum does not prove that a service is online, safe, controlled by the expected operator, or serving the content you expect.
Local input
Inspect an Onion Service address
Paste a v3 address, a bare 56-character service ID, or an http/https .onion URL.
Inspection result
Decoded Onion Service identity
Exact values
Address data
Interpretation
What the result means
Runs locally
Your Onion address stays in this browser.
Local input: Onion v3 service ID, hostname, or http/https URL. Network effect: none.
Onion addressBrowser decodeLocal checksum
After the same-origin page assets load, inspection works without internet access. Inputs are not added to the URL, browser storage, or site analytics.
Purpose and limits
Validate the address, not the service
What is not checked
No Tor circuit or network request is made. Availability, reachability, TLS, content, ownership, reputation, and operator identity remain unknown.
Subdomains and URLs
Only the rightmost 56-character service ID is self-authenticating. A subdomain, scheme, port, path, query, and fragment are separate and are not covered by the onion-address checksum.
V2 is obsolete
Legacy v2 addresses used 16-character service IDs. Current Tor clients use 56-character v3 addresses; the inspector recognizes v2 input and explains why it is rejected.
Vanity prefixes
A memorable prefix does not add trust. Treat the complete 56-character address as the identity and obtain it through a channel you trust.
Technical definition
The format is base32(public key | checksum | version). See the official Tor specification and v2 deprecation guidance.