Simple and basic, just pass an OA then get invited to final rounds. There's two final rounds:
Coding round - do a take home task where you have to design a cron parser then during the interview, you give a quick overview of the cron parser and then code up the extensions (You can easily find it online on GitHub. Extensions of the cron parser can be:
Supporting wrap around / cyclic notation
Including an optional year field
Allow both day names and month names to be displayed
Supporting arguments within the command
The next n occurence
Just code your submission to be extensible so you can easily add these extensions during the coding challenge.
System design:
Design a system where 6,000,000 (six million) free burgers are to be claimed, this will be a marketing campaign which lasts for 10 minutes. You only have to focus on the marketing campaign - the users are already logged in and you do not have to worry about users having to pay or how the burgers will be deliered. It is only 1 free burger per account. Focus on the scale, how the data flow will work from end to end, failure modes and observability (How will you monitor and observe everything during the event, what will you do before the event to ensure everything works as intended? What are potential bottlenecks in the system and any potential failures and how will you address them?) Cover tradeoffs made and why. How will you track the number of vouchers? What will you do if a user tries to claim a voucher again? what do you do before going live to ensure system works? now suppose system is live - how do you ensure system is working properly and services are healthy?
At the end, it is luck dependent and it depends on who your interviewer is, be wary that the interviewers do have a reputation for not being the best, especially when it comes to system design as you can see from other comments - just use this interview process as prep for other more important interviews at better companies because this place does have a glaring reputation for being toxic, not to mention how layoffs will be coming again thanks to doordash acquisition.
Then there is behavioural, super simple, basic questions asked, HOWEVER, be warned of toxic interviewers and getting downlevelled or even outright rejected yet again. There are countless stories of people unfairly getting downlevelled or outright rejected, I passed easily and guess luck was on my side this time.
Overall, it's an easy process and it's good practice for other more important interviews, though, the system design portion and their interviewers can be annoying to deal with. There is tons more information out there online too and do remember to check out what the culture is really like on the glassdoor reviews and reddit posts, talking to friends and colleagues who are current and past employees, deliveroo is not the place you want to end up at - keep trying your best to do better! The salary is below FAANG (obviously) and it is hybrid