Appendix

These pages are for use, not for reading through. Print the scorecard and the checklist, and keep the status table near the terminal.

Glossary

Term	Meaning
Allowlisting	Authorizing a client by its IP address instead of a password.
Antidetect browser	Browser that gives each profile its own fingerprint, storage and proxy.
ASN	Number that identifies the network owning an IP range.
Backconnect gateway	One hostname that forwards each request to a changing exit IP.
Backoff	Waiting longer after each failed attempt before retrying.
Cloud phone	Remote Android device with its own identity and proxy setting.
Concurrency	Number of requests in flight at the same time.
Datacenter proxy	IP hosted in a data center: fast, cheap, easier to flag.
Exit node	The device or server whose IP the target sees.
Fingerprint	Set of browser or client traits that can identify a visitor.
Geo-targeting	Choosing the country, region or city of the exit IP.
ISP proxy	Static IP on a server, registered to a consumer internet provider.
Jitter	Random variation in delays so clients do not retry together.
Mobile proxy	IP assigned by a mobile carrier to a device.
p95 latency	Time within which 95% of requests finish.
Residential proxy	IP assigned by a home internet provider to a household.
Rotation	Changing the exit IP per request or on a timer.
Scraper API	Service that fetches a URL and returns the page or data.
SOCKS5	Proxy protocol that carries any TCP traffic, and optionally UDP.
Soft block	A 200 response that carries wrong or missing data.
Sticky session	Keeping the same exit IP for a set time.
TLS fingerprint	Signature of a client's TLS handshake, such as JA3.
Unblocker	Managed proxy that handles fingerprints, retries and challenges itself.
WebRTC leak	Browser revealing the real IP through a WebRTC lookup.

Provider scorecard

These are the 12 criteria from Chapter 7, scored 1 to 5. Copy the worksheet once per provider and fill it in during the pilot.

Criterion	What to check	Score (1 to 5)
1. Pool and coverage	IPs in the countries and cities the job needs
2. Proxy types	The type needed now, plus the next rung up
3. Targeting	Country, region, city and carrier options in the plan
4. Session control	Sticky duration and rotation settings per connection
5. Pricing fit	Cost per 1,000 successful requests in the pilot
6. Trial and refund	Trial or refund terms stated before payment
7. Sourcing transparency	Written answer on consent and opt-out for device owners
8. Documentation	Public setup guides and working code samples
9. Support	Speed and quality of the reply to a technical question
10. Dashboard and API	Usage by day and target, sub-users, traffic limits
11. Compliance and KYC	Acceptable use policy and a real customer check
12. Reputation	A named company with a track record

Pre-launch checklist

Run through this list before a new scraper, profile or automation goes live.

• Exit IP, country and ASN confirmed from inside the app that does the work.
• No WebRTC or DNS leak in any browser profile.
• Timezone and language match the exit location.
• Credentials come from environment variables, and nothing secret is in the repository.
• Every request has a timeout, and TLS verification is on.
• Retries use backoff with jitter and a cap on attempts.
• Every response is checked for expected content, not only for status.
• Concurrency is limited per domain.
• A daily GB cap and a success-rate alert are in place.
• The legal questions are answered in writing, and robots.txt has been read.

HTTP status quick reference

A 407 always comes from the proxy, never from the target. A 502 or 503 can come from either. For HTTPS targets a proxy-side error shows up as a failed tunnel, while the target's own error arrives inside a normal response. Providers also add their own error codes, which their documentation explains.

Code	Name	Behind a proxy it usually means	What to do
200	OK	Success, or a soft block with wrong data	Validate the content
301 / 302	Redirect	A normal move, or a push to login or CAPTCHA	Check the final URL
403	Forbidden	Target refused the IP or the client fingerprint	Change the client, then the IP type
404	Not Found	Page is gone; now and then a disguised block	Do not retry; spot-check in a browser
407	Proxy Authentication Required	Wrong credentials, or the client IP is not allowlisted	Fix credentials or the allowlist
408	Request Timeout	Slow exit node or slow target	Retry with backoff
429	Too Many Requests	Rate limit per IP or per session	Slow down; honor Retry-After
500	Internal Server Error	Target failed while handling the request	Retry a few times
502	Bad Gateway	Proxy or exit node could not reach the target	Retry on a new IP
503	Service Unavailable	Target overloaded, a challenge page, or no exit available	Back off and inspect the body

Troubleshooting order

When requests fail, work from the bottom of the connection upward. Each layer is quicker and cheaper to check than the one after it.

1 · CredentialsA 407 or refused connection: check username, password, port and allowlist.

2 · ConnectivityTimeouts: test the gateway alone with curl and a 30-second limit.

3 · Exit IPConfirm the country, ASN and network type match the order.

4 · Rate429s or blocks after some pages: lower concurrency and add backoff.

5 · Client fingerprint403 on the first request: fix headers and TLS, or use a real browser.

6 · IP typeStill blocked: move to ISP, residential or mobile, then an unblocker.

ProxyLook's free tools

All six are free and run in the browser.

• What Is My IP shows the public IP, location, ISP and ASN a website sees.
• Proxy Checker returns the country, ASN, ISP and network type for a proxy IP.
• WebRTC Leak Test checks whether the browser exposes the real IP through WebRTC.
• User-Agent Parser breaks a user-agent string into browser, engine, system and device.
• Compatibility Checker suggests which proxy type fits a target site and use case.
• Proxy Cost Calculator estimates monthly spend from bandwidth and price per GB.

Key takeaways

• Score providers during a pilot on real targets, not on list price or pool size.
• Run the pre-launch checklist before every new scraper, profile or automation.
• A 407 comes from the proxy, and a 200 can still be a block.
• Troubleshoot in order: credentials, connectivity, exit IP, rate, client fingerprint, IP type.