How to Detect Proxy Interviewers in Coding Rounds

Proxy interviewing is when someone else performs the technical interview on behalf of the candidate.

It is one of the fastest-growing forms of interview fraud in remote engineering hiring.
This guide explains why it happens, the behavioral and technical signals to watch for, and how to confirm identity without confrontation.

Why Proxy Interviewing Happens

Remote work and contract-based hiring lowered the barriers to impersonation.
Candidates outsource the evaluation phase to a more skilled engineer.
Once hired, they either:

• Attempt to learn on the job

• Delegate work to the same proxy

• Disappear entirely after onboarding

This is not isolated.
It is a service market, with agencies advertising “we pass your coding rounds for you”.

The pattern has emerged alongside remote technical interviews, where identity verification and real-time skill validation are harder to enforce, making proxy participation and assisted coding interviews more feasible.

The Core Weakness Proxies Exploit

Most coding interviews test execution, not understanding.

Proxies are excellent at:

• Implementing patterns

• Reciting optimal solutions

• Performing well under structured problems

But they cannot fake:

• Personal thought process

• Tradeoff reasoning

• Debugging intuition

So detection must focus on reasoning, not correctness.

The Detection Framework: Look for Reasoning Stability, Not Output Quality

1. Break the Problem Into Stages

• Legitimate candidates

• Verbalize reasoning

• Show internal structure

• Adjust when constraints change

Proxies:

• Jump directly to code

• Do not share thinking

• Resist clarifying questions

Prompt:

Before coding, talk me through how you are thinking about solving this and why.

2. Introduce Constraint Changes Mid-Solution

Example:

Now assume the input size is one million. What changes?

A proxy will:

• Struggle to re-evaluate assumptions

• Try to return to rehearsed patterns

A real candidate:

• Recomputes complexity

• Evaluates memory and runtime tradeoffs

• Adjusts structure

3. Ask for a Debug Walkthrough

Not “fix this bug”.
Ask:

Where is this most likely to fail and why?

A proxy often:

• Cannot evaluate failure states

• Relies on pattern memory

A real engineer:

• Mentally simulates execution

• Mentions edge cases

4. Test for Ownership of Experience

Ask:

Where did you learn this pattern?
What alternative approaches did you consider?

A real candidate recalls:

• Team discussions

• Mentors

• Code reviews

A proxy answers:

• General textbook phrasing

• Memorized jargon

5. Request Implementation of a Variation

Example:

Now rewrite the solution to support streaming data instead of a static array.

This forces:

• Architectural reasoning

• Perspective shift

Proxies cannot adapt fluidly.
They revert to the original pattern.

Behavioral and Environmental Signals in Video

These are signals to probe, not proof.

Identity Verification Without Confrontation

Use neutral language:

For consistency across candidates, we do a quick identity verification step. Could you briefly show your workspace and confirm your audio source?

If they refuse:

• Pause the interview

• Require a follow-up verification session

Do not accuse.
Do not challenge.
Just follow the procedure.

Documentation Template (Legal Safe)

Candidate was unable to explain reasoning behind solution or adapt when constraints changed.
Provided correct implementation but could not articulate design tradeoffs.
Follow-up identity verification recommended before evaluation decision

Write what happened, not what you think happened.

Conclusion

Proxy interviewing is detectable.
Not through surveillance.
But through reasoning depth, adaptability, debugging intuition, and narrative ownership.

Do not test what they can write.
Test how they think.