How long does the Iliad / Free interview process take?

Most candidates spend between 4 and 8 weeks from recruiter screen to offer. The onsite loop itself runs in a single day or is split across two half-days, with debrief and offer typically within 5 business days after.

How should I prepare specifically for Iliad / Free?

Focus on three things: (1) the company DNA shown above — what they actually grade for, (2) the rounds in your loop, especially the round most candidates underestimate, and (3) drilling on the question types in this guide using a structured framework like CIRCLES or STAR.

Does this apply to engineering or design roles at Iliad / Free?

The DNA stays the same — what changes is the round mix. SWE candidates face coding screens instead of Product Sense; designers face portfolio reviews and design exercises. The "what they value" and behavioral signals carry across all functions.

Why are you interested in joining Iliad/Free, and what excites you about working in the telecom industry specifically?

Type: Motivation. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

Given a list of cell tower locations (latitude, longitude) and a user's current location, find the N closest cell towers. Consider the Earth's curvature for distance calculation.

Type: Algorithmic. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

Design an API for a new Iliad service that allows users to remotely manage their Freebox settings (e.g., Wi-Fi password, port forwarding). Consider security, scalability, and ease of use for developers integrating with it.

Type: API Design. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

How would you design a system to handle the signaling traffic for Iliad's mobile network, ensuring low latency and high availability, especially during peak hours or major events?

Type: Scalability. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

You are given a list of network connection events, each with a start time, end time, and source/destination IP addresses. Find the longest period during which a specific IP address was continuously connected to the network, possibly through multiple intermediate hops.

Type: Algorithmic (Hard). Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

Tell me about a time you had a significant disagreement with an engineer or designer about a product decision. How did you approach it, and what was the outcome?

Type: conflict resolution. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

Describe a time you took ownership of a project or problem that was outside your direct responsibility. What motivated you, and what did you achieve?

Type: ownership. Sign up at JobMentis to see the full framework, grading signals, and worked answer for this question.

Other roles at Iliad / Free:Product Manager Software Engineer Sales Marketing

Enterprise · Software Engineer Interview Guide

How to Pass the Iliad / Free Software Engineer Interview in 2026

The Iliad / Free DNA (TL;DR)

Iliad / Free values candidates who demonstrate a strong entrepreneurial spirit, technical prowess, and a drive to disrupt markets with innovative, cost-effective solutions. They seek individuals who are autonomous, customer-focused, and can thrive in a lean, fast-paced environment.

The Iliad / Free Interview Loop

Your onsite loop will typically consist of 5 rounds.

1
Round 1
Recruiter Screen
Motivation, role fit, logistics.
2
Round 2
Coding Screen
LeetCode-medium algorithmic problems under time pressure.
3
Round 3
System Design
Distributed systems, trade-offs at scale, architecture under constraints.
4
Round 4
Onsite Coding
LeetCode-hard, debugging, code clarity, edge cases.
5
Round 5
Behavioral / Leadership
Past evidence of ownership, influence, resolving conflict.

The Danger Zone: Top Reasons Candidates Fail

Based on our database of Iliad / Free interview outcomes, avoid these common traps:

Blaming the other party or portraying them as unreasonable without acknowledging their perspective.
Focusing on authority or pressure rather than persuasion.
Inefficient parsing logic, leading to slow processing of large log files.
Jumping to conclusions without analyzing relevant logs (router, ISP, client devices).

Test Yourself: Real Iliad / Free Questions

Three real prompts pulled from our database.

Type · Debugging

A Freebox router is intermittently dropping internet connections for users in a specific building. The logs show occasional 'DHCP lease renewal failures'. Debug this issue, identify potential root causes, and propose a fix.

Type · Data Structures

Design a system to efficiently track and report the number of active mobile users within specific geographic regions (e.g., cities, neighborhoods) in real-time. Assume data streams from millions of devices.

Type · Data Storage

Design a database schema and strategy for storing customer call detail records (CDRs) for Iliad. Consider the massive scale, the need for efficient querying (e.g., by customer ID, time range, call type), and data retention policies.

+ many more questions, signals, and worked examples

Unlock the rubric →

Iliad / Free Interview Question Bank

A sample from our database, grouped by round. Sign up to see the full set.

9 of 20 questions shown

Recruiter Screen

1
Type · Motivation
Why are you interested in joining Iliad/Free, and what excites you about working in the telecom industry specifically?

Coding Screen

2
Type · Algorithmic
Given a list of cell tower locations (latitude, longitude) and a user's current location, find the N closest cell towers. Consider the Earth's curvature for distance calculation.
3
Type · Data Structures
Design a system to efficiently track and report the number of active mobile users within specific geographic regions (e.g., cities, neighborhoods) in real-time. Assume data streams from millions of devices.
+ 1 more questions in this round (sign up to unlock)

System Design

4
Type · API Design
Design an API for a new Iliad service that allows users to remotely manage their Freebox settings (e.g., Wi-Fi password, port forwarding). Consider security, scalability, and ease of use for developers integrating with it.
5
Type · Scalability
How would you design a system to handle the signaling traffic for Iliad's mobile network, ensuring low latency and high availability, especially during peak hours or major events?
+ 1 more questions in this round (sign up to unlock)

Onsite Coding

6
Type · Algorithmic (Hard)
You are given a list of network connection events, each with a start time, end time, and source/destination IP addresses. Find the longest period during which a specific IP address was continuously connected to the network, possibly through multiple intermediate hops.
7
Type · Debugging
A Freebox router is intermittently dropping internet connections for users in a specific building. The logs show occasional 'DHCP lease renewal failures'. Debug this issue, identify potential root causes, and propose a fix.
+ 1 more questions in this round (sign up to unlock)

Behavioral / Leadership

8
Type · conflict resolution
Tell me about a time you had a significant disagreement with an engineer or designer about a product decision. How did you approach it, and what was the outcome?
9
Type · ownership
Describe a time you took ownership of a project or problem that was outside your direct responsibility. What motivated you, and what did you achieve?
+ 8 more questions in this round (sign up to unlock)

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Interview tracks at Iliad / Free

How Iliad / Free's DNA translates across functions. Pick your role.

SWEs are expected to demonstrate strong technical skills, especially in networking, infrastructure, and scalable systems, crucial for Free Mobile and Freebox services. They value problem-solvers who can build robust, efficient, and cost-effective solutions with minimal oversight.

Debugging

Data Structures

+ 1 more

Unlock the Software Engineer grading rubric for Iliad / Free

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