What is Shared Proxy?
A shared proxy carries traffic from several customers through the same exit IP or the same pool of addresses. Sharing spreads the cost of the underlying line across users, which is why shared plans price lower per gigabyte. What you give up is control, since another customer's activity shapes the reputation of the address you send through.
Three things get shared, and providers rarely separate them. The exit address is the obvious one. The upstream capacity of the line is the second, so on a mobile setup several customers routed through one modem contend for the same radio link and your throughput moves with what everyone else is doing. The third is the concurrency budget, since a modem's NAT table and the provider's own limits are finite. A quiet shared line and a busy one perform nothing alike, and the plan description will not tell you which you got.
Blocking is mostly per-site, which explains the strangest behaviour of shared proxies. If another customer runs an aggressive job against one social platform from that address, your requests to that platform inherit the block while the same address stays clean everywhere else. Test against the target you care about rather than against a generic proxy checker. A shared endpoint that returns a CAPTCHA on the first request to a site, at a request rate no human would notice, has already been burned there by someone else.
There is a real argument for sharing on residential and mobile ranges. Those addresses already carry a crowd. Mobile lines in particular sit behind carrier-grade NAT, where many genuine subscribers leave through one public IP, so traffic from a handful of proxy customers arrives inside normal-looking noise. Datacenter shared proxies have no such cover. The whole range is identifiable as hosting, and several customers hitting one target from one address makes the pattern easier for a detection system to isolate.
Ask what isolation the provider does apply. Some route each customer through separate sub-users with their own credentials and rate limits, and a few assign a customer to a single target platform so two people never hit it from one address. Plenty do neither. Sub-user credentials also give you usable logs, since a support ticket about a block can be answered when the provider can see which account generated the traffic on that IP.
Where you meet it
The choice shows up on nearly every provider's pricing page - a cheap shared plan next to a private one at several times the price. Judge it against your workload rather than the label. Run the shared endpoint at your target and watch for CAPTCHAs appearing at low request volumes, which is the usual sign of an address someone else already spent. PROXIES.SX prices bandwidth only, $4/GB dropping to $2.40/GB at volume, so there is no shared or private tier to choose between.
Common questions
Why does a shared proxy work on one site and not another?
Because most blocks are issued per site. An address flagged by one retailer after another customer's scraping run keeps a clean record at every other destination. Reputation is not a single global score, so an IP can be worthless for the one platform you need and perfectly usable everywhere else.
Are shared proxies safe for account logins?
They are risky for anything long-lived. A platform can link accounts that log in from the same address, so you may be joined to a stranger's activity on that IP without knowing. For account work, an address only you use is the safer setup; shared endpoints suit stateless collection where a block costs you a retry.
How many people share one shared proxy?
Providers rarely publish the ratio, and it changes with load. The practical test is measurement. Run a throughput check at several times of day and send repeated requests to your target. Wide swings in speed or blocks that appear without any change on your side point at heavy sharing on that line.
Related terms
Real 4G/5G mobile and residential IPs
PROXIES.SX runs carrier IPs in 100+ countries with HTTP and SOCKS5 on every endpoint. $4/GB down to $2.40/GB at volume, free endpoints and rotation, and your GB never expire.