DataLemur vs PracHub (2026): Which Is Better for Data Interviews?

DataLemur is a small, curated SQL and data science drill site built around an in-browser editor. PracHub is a bank of real, recently asked interview questions with in-depth written solutions, most of them free. For a data scientist or analyst loop, PracHub is the better first stop because it shows what your target company asks across SQL, experimentation and statistics. DataLemur is worth its $60 a year (as of October 2026) only after you know SQL syntax is your weak spot.

Pricing and product details were checked on October 14, 2026.

TL;DR

• Choose DataLemur when your next round is a SQL screen and you want an editor with hints over a short list. Logged out, its catalog showed 106 questions on October 14, 2026, and 54 of them were SQL.
• Choose PracHub when you need to know what Amazon, Google or a smaller company has recently asked data people, across SQL, analytics and experimentation, and statistics, and you want to start free.
• Use both when the loop is on the calendar: diagnose with free PracHub company questions, patch syntax gaps on DataLemur's free tier, and pay for either one only after that.

At a Glance

Coverage and Depth

DataLemur's catalog is small, and its own numbers do not agree with each other. On October 14, 2026 the logged-out question list showed 106 items across 46 company labels. The pricing page promises "100+" SQL questions, "70+" data science questions, "200+" in its meta description and "250+" in the lifetime bundle. Only 13 of the visible questions were statistics, machine learning or probability. Company depth is thin: seven questions are filed under the generic label "FAANG", 22 companies have exactly one question, and only Amazon (11), Facebook (9), Google (7) and Microsoft (5) reach five. A competing site's comparison describes the Python items as generic algorithm exercises such as Two Sum and Roman to Integer rather than data-processing tasks. The terms add that DataLemur "does not make any commitment to update the materials", so recency is not something it promises.

As of October 2026, PracHub lists more than 12,000 questions across every role from more than 500 companies. Its data categories alone hold more than 700 SQL and Python data-manipulation questions, more than 900 in analytics and experimentation and more than 600 in statistics and math. Large employers go deep: Amazon has more than 800 questions across all roles, Google more than 600 and Capital One more than 350, against DataLemur's 11, 7 and fewer than five for Capital One.

Asked at Glean: SQL: Zero-Filled DAU, Rolling 30-Day MAU, and the MAU Impact of a User-ID Rehash A data scientist SQL round that fit five questions with follow-ups into one hour. You build daily actives with zero-filled gaps, a rolling 30-day MAU, and then reason about what a user-ID rehash does to the MAU line.

Solution Depth

DataLemur gives hints and full solutions with Premium, according to its pricing page. Which solutions are free is unknown: the public catalog does not mark access, and the free tier's limits are not spelled out. Difficulty labels are loose. On the 2022 Show HN thread a commenter said a hard problem felt easy and a medium felt hard, and the founder replied that difficulty is set "just off the vibes". Its terms also state that the site will not promise its materials are accurate, complete or current.

PracHub's written solutions are the product. As of October 2026 more than 7,000 questions carry one. Most questions are free to read, more than 1,100 have both a free question and a free solution, and many of the full written solutions sit in the optional paid tier.

Asked at Google: How would you use propensity score matching here A recommender feature was not randomized, and more engaged users were more likely to opt in. You have to explain how you would estimate its effect on 7-day retention from observational data.

Free Access

DataLemur calls itself freemium. Its terms say plainly that it "does not offer any discounts or free trials", only free accounts or paid subscriptions. The catalog is visible without logging in, and the footer links a free 9-day data interview crash course and a free SQL tutorial. The problem is that you cannot tell from the public list which of the 106 questions you can finish without paying.

On PracHub, most questions are free: more than 8,000 of the 12,000-plus visible questions across all roles as of October 2026.

Asked at Amazon: Find recommended friend pairs by shared songs A data scientist SQL question on a music app: from a listens table and an undirected friendships table, find the user pairs that qualify as recommended friends on a given calendar date.

That question is free to open, so you can test yourself against a real Amazon data prompt before paying.

Practice Tools

This is where DataLemur wins outright. Its in-browser SQL editor with multiple hints is a better tool for drilling window functions, CTEs and joins than reading a solution. We could not confirm on its own site which SQL dialect the editor runs, so check it against your target company's warehouse. Its filters list SQL, Probability, Statistics, Machine Learning and Python only.

PracHub is a question bank first: read the real prompt, write your answer, compare it with the written solution. That covers the rounds an editor cannot, such as experiment reads, where the grade comes from your reasoning.

Asked at Waymo: Conservative Wait Estimates Cut Conversion and Pickup Time: Did Efficiency Improve? A timed online assessment case: a ride service started showing deliberately high wait estimates, conversion fell 5% and actual pickup time fell too. You decide whether the service got more efficient.

Price and Refunds

As of October 14, 2026, DataLemur charges $15 a month or $60 a year. The yearly plan is shown as "$5 per month" beside a struck-through $180. A $300 one-time bundle adds a one-hour call with founder Nick Singh, a signed copy of his book and lifetime access. Its own blog comparison with StrataScratch quotes Premium at $10 a month, which contradicts the pricing page. The terms are strict: fees are non-refundable except where law requires, refunds are considered case by case by emailing the founder, cancelling only stops renewal, and prices can change without notice. Support runs through one personal mailbox, and /faq and /refund return 404.

PracHub is free to start with an optional paid tier, and its current price and terms sit on the pricing page linked in the table above. Because most questions are free, you can judge the bank on your own target company before you pay.

When DataLemur Is the Better Choice

• Your next round is an analytics SQL screen on joins, window functions and CTEs, and you want a short, curated list in an editor with hints instead of a big bank.
• You are on a tight budget. $60 a year (October 2026) is cheap, and the free SQL tutorial and 9-day crash course cost nothing.
• You own Ace the Data Science Interview and want to work its questions interactively; 28 questions on the site were tagged to the book when checked on October 14, 2026.
• You are aiming at Amazon, Meta or Google SQL screens, the deepest company tags on the site.
• You want founder coaching bundled with a signed book and lifetime access for a one-time $300.

Our honest DataLemur review goes further on whether it is enough on its own, and the LeetCode SQL vs DataLemur comparison covers the pure-SQL choice.

When PracHub Is the Better Choice

• You have a loop at a specific company and want the questions it has actually asked, tagged by role.
• Your loop includes more than SQL: experiment design, causal inference, metrics, statistics or an ML round.
• You want to start free and see what is asked before deciding whether to pay.
• Your target is a company DataLemur covers with one question or not at all, which is true of 22 of its 46 labels.

Using Both

1. Start on your target company's page from the company list. Read ten recent questions for free and write down which rounds keep coming up.
2. If SQL dominates, work the SQL and pandas questions for that company first. Note where your syntax breaks, not where your logic does.
3. Patch those syntax gaps on DataLemur's free tier and its free SQL tutorial. Pay for its yearly plan only if the editor drills are clearly helping.
4. Spend the rest of your time on analytics and experimentation questions, where written solutions beat an editor.
5. In the final week, stop adding new material and re-read the newest questions from your target company.

If you are also weighing StrataScratch or Interview Query, the three-way comparison sets those against DataLemur.

Practice these on PracHub

Start with questions from real data science loops, grouped by the round they belong to. Each of these was free to open when checked on October 14, 2026.

• SQL and pandas (Amazon: friend pairs by shared songs · Glean: zero-filled DAU and rolling MAU); more in the SQL and pandas questions.
• Analytics and experimentation (Google: propensity score matching · Waymo: conservative wait estimates); more in the analytics and experimentation questions.
• Statistics and math (Microsoft: classification metrics under asymmetric costs); more in the statistics and math questions.

Then browse every data scientist question, the SQL interview questions page or the full question bank.

Frequently Asked Questions

Is PracHub better than DataLemur?

For most data scientist and analyst loops, yes, as the place to start. As of October 2026 PracHub lists more than 12,000 questions across all roles from more than 500 companies, including more than 700 SQL/Python, 900 analytics and experimentation and 600 statistics questions, and most questions are free. DataLemur is better at one job: drilling SQL syntax in its in-browser editor with hints.

Is PracHub free, and is it worth it?

PracHub is free to start with an optional paid tier. Most questions are free (more than 8,000 as of October 2026), and many of the full written solutions sit in the paid tier. It is worth it when you have a loop at a specific company, because you can read what that company asked before you pay anything. Current terms are on the PracHub pricing page.

Is DataLemur free?

Partly. Free accounts exist and DataLemur calls itself freemium, but its terms say it offers no discounts or free trials, and its public catalog does not mark which questions are free. Premium cost $15 a month or $60 a year when checked on October 14, 2026.

Does DataLemur have solutions?

Yes. Its pricing page says Premium includes multiple hints and full solutions. Its public pages do not say which solutions, if any, are free.

Can I use DataLemur and PracHub together?

Yes, and for SQL-heavy loops that is the best setup. Use free PracHub company questions to learn which rounds you face, drill SQL syntax on DataLemur's free tier, and pay for either one only once the loop is scheduled.

Which is better for data scientist interviews?

PracHub, because data scientist loops go past SQL into experimentation, causal inference and statistics. On October 14, 2026 only 13 of DataLemur's 106 logged-out questions covered statistics, machine learning or probability, while PracHub listed more than 900 analytics and experimentation questions and more than 600 statistics questions.

Final Verdict

DataLemur is a good SQL drill tool wrapped in strict terms. It is cheap at $60 a year, but the catalog is small, its own pages disagree about its size, and fees are non-refundable unless the law requires a refund or the founder grants one case by case. Treat it as a syntax gym, not a map of what you will be asked.

PracHub is the better place to start a data interview loop because it is built from real, recently asked questions and most of them are free. Start with the data scientist questions, and add DataLemur only if SQL syntax is what is holding you back.