Proxy checker
Paste up to ten proxies and check each one: whether it is alive, the exit IP it presents, the network that owns it, its country and city, and how long it took to answer. A browser cannot connect through an arbitrary proxy from a page, so this part runs on our server — which keeps no record of what you paste.
What we keep: nothing. Credentials are used for that one check and never logged. Use a test credential if your provider gives you one. Private and reserved targets are refused, and there is a limit of 30 proxy checks per hour. The residential-or-datacentre read is a hint from the network owner’s name, not a verdict.
Alive, and where it exits
A proxy is only useful if it answers and presents the exit you expect. The check completes the real handshake — HTTP CONNECT or the SOCKS5 greeting and auth — then reads the exit address through the tunnel, so “alive” means a request actually went out and came back.
Alive
The proxy answered and tunnelled a request. You get the exit IP, its owner, country and city.
Auth failed
The credentials were rejected at the handshake — the username or password step for SOCKS5, or a 407 for HTTP.
Refused / timed out
The proxy did not complete a connection, or did not answer in time. Often a dead host, wrong port or wrong type.
Exit IP and owner
The address a site would see, and the network behind it. A datacentre owner behind a “residential” claim is a common tell.
- Paste your proxies. Paste up to ten proxies, one per line, in any common format — host:port, host:port:user:pass, or user:pass@host:port.
- Check them. Our server opens a connection to each proxy, completes the HTTP or SOCKS5 handshake, and requests an IP echo through it.
- Read the result. For each proxy you get alive or the step that failed, the exit IP, its ASN and network owner, country and city, and the connect latency.
Can a website check a proxy from my browser?
No — browsers cannot open a connection through an arbitrary proxy from a page, so this check runs on our server. It opens a socket to the proxy, completes the HTTP or SOCKS5 handshake, and reads the exit IP through it.
What do the results mean?
Alive with an exit IP means the proxy answered and tunnelled a request. Auth failed means the credentials were rejected at the handshake. Refused or timed out means the proxy did not complete a connection. The country and network owner are read from the exit address.
Is the residential-or-datacentre label reliable?
Treat it as a hint from the network owner’s name, not a verdict. It is read from the AS organisation behind the exit IP; a provider can sit on networks that do not match the label.
Are my proxy credentials safe?
They are used only for that one check and are never logged. Still, use a test credential if the provider gives you one. Mosaic itself checks a profile’s proxy before every launch and refuses to open behind one that has not answered.
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