Free tools

SQL Formatter

Format messy SQL into clean, readable queries instantly.

A/B Test Calculator

Check statistical significance, lift and experiment results.

Descriptive Statistics Calculator

Mean, median, mode, standard deviation and quartiles from a paste of numbers.

Sample Size Calculator

How many visitors per variant your A/B test needs, worked out up front.

Correlation Calculator

Pearson r, r², a scatter plot and a significance test from two columns.

Percentage Change & CAGR

Percentage change between two values, or compound growth over many periods.

JSON ⇄ CSV Converter

Convert CSV to JSON or JSON to CSV, both directions, in your browser.

CSV Cleaner & Viewer

View a CSV as a table, trim whitespace, drop empties and dedupe.

Regex Tester

Test a regular expression with live highlighting and capture groups.

SQL Joins Visualizer

See what INNER, LEFT, RIGHT and FULL JOIN return on the same tables.

Confidence Interval Calculator

A confidence interval for a mean (t) or a proportion (normal).

Excel Formulas Cheat Sheet

The Excel & Sheets formulas analysts use, with syntax and examples.

Salary Calculator

Typical pay by role and experience level, from live job posts on Gigsouk.

Resume ↔ Job Matcher

Compare your resume with any job description.

Resume Bullet Builder

Turn what you did into strong, metric-driven resume bullets.

Tech Skills Checklist

Data, full stack, AWS, GCP, Azure, DevOps and more — tick what you know, see what to learn next.

Data Analyst Interview Questions

A bank of real questions with answers, by topic and difficulty.

SQL Case Study Practice

Practice SQL with realistic business analytics problems.

How to Become a Data Analyst

A free five-phase roadmap — SQL, stats, viz and a portfolio.

How to Become an AI Analyst

What the role is, and the path built on analyst foundations.