Quant Interview Prep Resources: Best Free and Paid Options
The best free and paid quant interview prep resources in 2026: books like the green book and Heard on the Street, prep platforms, mental math tools like Zetamac, coding resources, and communities — matched to role and prep stage.
Candidates deciding which books, platforms, drills, and communities to actually use for quant interview prep.
Pick resources by job to be done
Different resources solve different problems. Books teach methods and give deep problem sets. Platforms give volume, feedback, and structure. Mental math tools build speed. Communities answer process questions. Diagnostics tell you what to work on first. A resource is good if it trains your current bottleneck; most candidates need one from each category, not five from one.
Books: the classics still earn their place
Two books cover most of the ground. A Practical Guide to Quantitative Finance Interviews by Xinfeng Zhou, universally called "the green book," is the standard problem collection: brainteasers, probability, stochastic processes, and finance, with terse solutions that reward working problems before reading answers. Heard on the Street by Timothy Falcon Crack is broader and older, strong on brainteasers and finance-logic questions with fuller discussion. For pure probability depth, Fifty Challenging Problems in Probability by Frederick Mosteller is short, cheap, and brutal in the best way. Books are the cheapest paid resource per hour of practice, but they give no feedback loop: you will not know whether a miss was a one-off or a pattern unless you keep your own error log.
Platforms: structure versus question volume
Prep platforms split into structured curricula that teach methods before testing them, and question banks that assume you learn from solutions. LeetQuidity is built as the former: a sequenced probability curriculum with lectures, worked solutions, drills, games, and a free diagnostic. Question banks like QuantGuide and Quantable suit candidates who already know the theory and want volume. The right choice depends on whether your gap is knowledge or reps — our full platform comparison walks through pricing, free tiers, and features for every major option, and the honest answer is that different candidates should pick different tools.
Mental math: Zetamac and timed drills
Zetamac's arithmetic game is the default mental math tool for trading interviews: free, browser-based, keyboard-first, and close in spirit to the timed arithmetic screens several trading firms use. Treat it as a daily ten-minute habit rather than a cram tool, and track your score weekly. Several paid platforms add firm-styled variants and progress tracking, which helps if plain Zetamac scores plateau, but nobody fails a trading screen for having practiced only on the free tool.
Coding: use a dedicated resource
For coding rounds, use a coding-specific resource. LeetCode remains the standard for data structures and algorithms practice, and its free tier covers most of what quant developer and researcher screens test; language fluency in Python or C++ matters more than exotic problems. LeetQuidity does not currently claim complete coding-interview preparation, so pair it with a coding tool if your target role has a programming round — quant developer candidates should weight coding practice at least as heavily as probability.
Communities and mock interviews
QuantNet forums, the r/quant subreddit, and university quant societies are useful for process questions: timelines, what a given firm round looks like, and resume feedback. Treat compensation threads and offer anecdotes as noisy samples, not data. For mocks, a prepared peer asking follow-ups is worth more than a passive video; trade mock interviews weekly in the final month.
Recommendations by role and stage
Early-stage trading candidates: the green book plus a structured curriculum plus daily Zetamac. Early-stage research candidates: the same, with more statistics reading and LeetCode for the coding round. Quant developers: LeetCode first, probability second. Final month, any role: shift from learning to timed mixed practice, mocks, and repairing repeated misses. If you can only pay for one thing, buy whichever fixes your bottleneck: a book if you lack methods, a platform if you lack structure and feedback, nothing if you lack only arithmetic speed — Zetamac is free.
Common mistakes
The classic failure is collecting resources instead of practicing: three books, four platform accounts, and no error log. Keep one source for explanations, one for problems, one speed drill, and one way to test yourself. Switch only when the current tool cannot train the missing skill, and use a diagnostic like the free LeetQuidity calibration to decide what the missing skill actually is.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.