Firecode.io

Last updated: March 18, 2026

Coding interview prep, done right. Firecode.io is the #1 spaced-repetition coding interview preparation platform, built by Fireflo LLC. Trusted by over 50,000 software engineers who have landed six and seven-figure offers at Google, Meta, Amazon, Microsoft, Netflix, OpenAI, and more.

Why Firecode?

Traditional coding interview prep is broken. You solve hundreds of problems, but forget the patterns within a week. You grind for months, then freeze in the actual interview. Firecode fixes this with memory science.

Firecode's SM2-boosted adaptive learning engine tracks your performance on every problem and schedules reviews at scientifically optimal intervals. Instead of randomly grinding, you practice the right problems, at the right time, for the right number of repetitions.

Key Features

  • 1,500+ real interview problems — Fresh, company-sourced questions added regularly. Covers arrays, strings, trees, graphs, dynamic programming, and more.
  • 14 programming languages — Java, JavaScript, Python, C++, Go, Scala, Kotlin, Ruby, TypeScript, Swift, C#, PHP, Dart, and Rust.
  • Spaced repetition engine — SM2-boosted algorithm adapts to your personal forgetting curve for maximum retention on interview day.
  • AI-driven adaptive learning — The engine selects your next problem based on your goals, skill level, and interview timeline.
  • Gamification — Streaks, milestones, badges, and progress tracking keep you motivated without burning out.
  • Expert-curated hints and solutions — Every problem includes step-by-step hints and detailed, optimized solutions with complexity analysis.

Results

Engineers using Firecode have received offers from Google, Meta, Amazon, Microsoft, Netflix, Apple, OpenAI, Stripe, and many more top tech companies. The highest reported total compensation from a Firecode user is $1.6M per year. Most users practice just 15-30 minutes per day for 3-6 months.

Get Started

Visit firecode.io to start your free trial. No credit card required. Join 50,000+ engineers who prep smarter, not harder.

Frequently Asked Questions

What is Firecode.io?

Firecode.io is a coding interview preparation platform built by Fireflo LLC. It uses spaced repetition and an AI-driven adaptive learning engine to help software engineers practice and retain data structures and algorithms — the core skills tested in technical interviews at companies like Google, Meta, Amazon, and Microsoft.

How many problems does Firecode have?

Firecode has over 1,500 real coding interview problems, sourced from actual interviews at top tech companies. New problems are added regularly to keep the question bank fresh and relevant.

What programming languages does Firecode support?

Firecode supports 14 programming languages: Java, JavaScript, Python, C++, Go, Scala, Kotlin, Ruby, TypeScript, Swift, C#, PHP, Dart, and Rust. You can switch languages at any time.

What is spaced repetition and how does Firecode use it?

Spaced repetition is a memory science technique that schedules reviews at increasing intervals to maximize long-term retention. Firecode's SM2-boosted learning engine tracks your performance on each problem and automatically schedules when you should review it next — so you retain patterns for interview day instead of forgetting them within a week.

How is Firecode different from LeetCode?

While LeetCode is a problem repository, Firecode is a guided learning system. Instead of grinding thousands of problems randomly, Firecode's adaptive engine selects the right problems at the right time based on your personal forgetting curve. Engineers typically practice 15-30 minutes a day with Firecode versus hours of unstructured grinding on LeetCode.

Is Firecode free?

Firecode offers a free tier to get started. Premium plans unlock full access to all 1,500+ problems, advanced spaced repetition features, and detailed progress analytics. A 7-day free trial of Premium is available with no credit card required.

Who uses Firecode?

Over 50,000 software engineers have used Firecode to land six and seven-figure offers at top tech companies including Google, Meta, Amazon, Microsoft, Netflix, OpenAI, and more. The highest reported total compensation from a Firecode user is $1.6M/year.

How long does it take to see results with Firecode?

Most users see meaningful improvement within 2-4 weeks of consistent daily practice (15-30 minutes per day). For best results preparing for a specific interview, we recommend starting 3-6 months in advance. The spaced repetition engine adapts to your schedule and goals.

Who created Firecode.io?

Firecode.io is created and maintained by Fireflo LLC, a product innovation lab based in San Francisco, CA and Tampa, FL. Fireflo LLC was founded in 2023 and builds software products that help people learn, create, and grow.