Valon Interview Questions & Experiences

Valon·Software Engineer·Technical Phone Screen

Jul 2026

Valon Mortgage gave me a coding round that was basically 'build a tiny in-memory database from scratch.' One question, but it sprawled in every direction once I started implementing it.

Design and implement a simplified in-memory database that supports INSERT, SELECT with column projection, WHERE filtering, and ORDER BY on a single fixed-schema table.

“I started with the insert and select logic pretty confidently, but the WHERE clause is where things got messy.”

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Valon·Software Engineer·Technical Phone Screen

Jun 2026

Valon software engineer round where they gave me a schema-less in-memory database to build from scratch. Pretty open-ended, which I liked but also found a bit stressful since there's no clear stopping point.

Design and implement a simple in-memory database that supports schema-less records, where each record is a key-value mapping of column names to values, and different records can have completely different columns.
Extend the query interface to support filtering records by one or more column conditions, and define what happens when a filter references a column that doesn't exist in a given record.

“The open-ended API design part tripped me up more than the actual coding.”

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Valon·Software Engineer·Technical Phone Screen

Jun 2026

Valon SWE interview had me building an in-memory database from scratch, no test harness provided, just write your own cases and defend your design. The follow-up on arbitrary multi-column filtering is where things got interesting and also where I started second-guessing my index design.

Design and implement an in-memory database with a flexible schema (different rows can have different columns), supporting insert, find-by-column, and find-by-column-value operations. Write your own test cases.
Extend your database to support filtering by an arbitrary combination of column-value predicates. Then discuss the data structures involved, insert vs. query cost tradeoffs, and how you'd handle range queries or missing columns.

“The schema flexibility part is what tripped me up at first.”

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Valon·Software Engineer·Technical Phone Screen

Jun 2026

Valon software engineer interview had me extending a basic in-memory database to support filtered selects. Pretty focused session, one meaty coding problem with a design discussion tacked on at the end.

You have a simple in-memory database that supports INSERT and basic SELECT. Extend SELECT to accept a filter argument that matches rows on one or more column-value equality conditions. Walk through your implementation and then discuss how you'd generalize to other operators and add indexing.

“The equality filter part was fine, just iterate rows and check every predicate.”

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Valon·Software Engineer·Technical Phone Screen

May 2026

Valon software engineer interview focused on object-oriented design, specifically building out a class that manages employee records. Pretty straightforward premise but the follow-ups pushed into territory I wasn't fully prepared for.

Design a Company class that manages a collection of Employee objects. Employees have an id, name, and email, with id as the unique immutable key. Implement get by id, update email, and delete. How do you handle secondary lookups by name or email, and what happens when an id doesn't exist or an email is already taken?

“Started with a hash map keyed by id, which felt obvious, and the interviewer seemed fine with that.”

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Valon·Software Engineer·Technical Phone Screen

May 2026

Second part of a coding round at Valon for a software engineer role, focused on extending a SQL-like parser to handle IN clauses.

You've built a basic SQL SELECT parser. Now extend it to support IN clauses, like SELECT name IN xxx.

“This was a follow-up to whatever part one was, so I came in mid-flow.”

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Valon·Software Engineer·Technical Phone Screen

May 2026

Interviewed at Valon for a Software Engineer role. The format was unconventional, screen sharing was required, and only Google was allowed. Part 3 of the coding problem involved adding filter-by functionality, and I didn't make it through.

Extend an existing implementation to support filter-by functionality.

“This was part 3 of a multi-part problem and it's where things fell apart for me.”

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Valon·Software Engineer·Technical Phone Screen

May 2026

Valon software engineer interview that went pretty deep into OOP fundamentals. One question, but it had a lot of layers to it and the discussion kept branching out further than I expected.

Design an Employee class with id, name, and email fields. Cover the constructor, getters/setters, equality based on id, input validation like email format, and discuss how immutability, hash consistency, and composition into a larger company/manager system would work.

“Started fine with the basics but the follow-up about hashCode consistency with equality is where I stumbled a bit.”

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Valon·Software Engineer·Technical Phone Screen

May 2026

Valon SWE interview had me extending a toy in-memory database, which sounds straightforward until you're mid-explanation and realize you forgot to think about sort stability. Pretty focused technical round, one meaty coding design problem with a bunch of follow-up discussion baked in.

You have a basic in-memory database that supports INSERT and a simple filtered SELECT. Extend it to support ORDER BY with a specified column and direction, where ties are broken by insertion order. How do you implement this, and what are the time complexity implications for the full query pipeline?
How would you handle sort stability in this context, and what happens if the ORDER BY column contains mixed types or null values?

“I started with the obvious approach: run the filter, project columns, then sort.”

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Valon·Software Engineer·Technical Phone Screen

Apr 2026

Valon software engineer coding round where the task was to implement a working file system with full test coverage. A lot of code, not much prep, and it showed.

Implement a file system in code, including writing full test cases that pass.

“I didn't finish.”

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