How the OSSU Computer Science Curriculum Is Structured: A Complete Guide to the Free CS Degree

The OSSU computer science curriculum is organized into five sequential layers—Prerequisites, Intro CS, Core CS, Advanced CS, and a Final Project—mapping exactly to the CS 2013 guidelines, with all course materials curated in modular coursepages/ directories and tracked via simple Markdown checkboxes in the repository's README.md.

The ossu/computer-science repository provides a fully open-source, self-paced educational path that replicates the requirements of a traditional undergraduate computer science degree without tuition costs. This curriculum structures freely available MOOCs, textbooks, and university lectures into a rigorous progression governed by the Curricular Guidelines for Undergraduate Degree Programs in Computer Science (CS 2013). By following the repository's hierarchy, learners move from high-school math foundations through advanced electives to a capstone project that demonstrates mastery.

The Five-Layer Architecture of the OSSU CS Curriculum

The curriculum is designed as a vertical stack where each layer builds upon the previous, starting with remedial math and culminating in independent research.

Prerequisites and Intro CS

Before attempting university-level material, learners must demonstrate proficiency in high-school algebra, geometry, and pre-calculus as specified in the Prerequisites section of README.md.

Once ready, students complete Intro CS, a single "taste-test" course that introduces computation, imperative programming, and basic data structures. The repository directs learners to Introduction to Computer Science and Programming using Python, with specific guidance located in [coursepages/intro-cs/README.md](https://github.com/ossu/computer-science/blob/master/coursepages/intro-cs/README.md).

Core CS: The Eight Sub-Domains

Core CS represents roughly the first three years of a bachelor's program and is divided into eight distinct sub-domains. Each sub-domain maintains its own directory under coursepages/ containing a README.md with course links, prerequisites, and effort estimates.

The eight sub-domains are:

• Programming – Foundational software engineering courses like Systematic Program Design ([coursepages/spd/README.md](https://github.com/ossu/computer-science/blob/master/coursepages/spd/README.md))
• Math – Calculus and discrete mathematics sequences, including MIT's Calculus 1A-C via OpenLearning
• Tools – Essential developer tooling covered in The Missing Semester of Your CS Education (coursepages/cs-tools)
• Systems – Hardware and operating systems, including Build a Modern Computer from First Principles (Nand-to-Tetris) referenced in coursepages/ostep
• Theory – Algorithm analysis and complexity theory via Stanford's Algorithms: Design and Analysis
• Security – Foundational cybersecurity through Cybersecurity Fundamentals on EDX
• Applications – Practical domains such as Databases: Modeling and Theory
• Ethics – Professional responsibility and societal impact via Ethics, Technology and Engineering

Advanced CS Elective Tracks

After completing all Core CS requirements, learners select from Advanced CS elective tracks to specialize or deepen expertise. These tracks are optional but recommended for mastery:

• Programming – Advanced paradigms like Parallel Programming (Scala)
• Systems – Deep dives such as Compilers (EDX)
• Theory – Formal methods including Theory of Computation (MIT OCW)
• Information Security – Specialized security courses like Web Security Fundamentals
• Math – Linear algebra and advanced statistics via resources like Essence of Linear Algebra

The Final Project

The curriculum concludes with a capstone project where learners independently design and deliver a solution to a real-world problem. This project demonstrates integration of knowledge across all prior layers and is self-directed without prescribed course materials.

Navigating the Repository Structure

The ossu/computer-science repository functions as a lightweight learning-management system using only Markdown and Git.

Key Files and Their Purpose

Understanding the repository layout is essential for efficient progress:

File	Purpose
README.md	The master curriculum containing the full course hierarchy, effort estimates (in hours), and Discord/forum links for community support
CURRICULAR_GUIDELINES.md	Verbatim reproduction of the CS 2013 standards that justify the curriculum's scope and sequence
CONTRIBUTING.md	Community guidelines for proposing new courses or updating broken links via pull requests
coursepages/<topic>/README.md	Granular sub-domain details (e.g., coursepages/spd/, coursepages/ostep/)
extras/readings.md	Supplementary classic textbooks and free online readings for deeper study

Tracking Progress with Git

Because the curriculum is pure Markdown, learners track completion by editing README.md directly. The community convention is to append a ✅ emoji to course lines upon completion.

Clone the repository to begin:

git clone https://github.com/ossu/computer-science.git
cd computer-science
code README.md  # Opens in VS Code or similar

Automate progress tracking with the following Python script saved as mark_done.py:

import sys, re

def tick_course(course_name, path='README.md'):
    with open(path, 'r', encoding='utf-8') as f:
        lines = f.readlines()

    pattern = re.compile(rf'^(\s*\[.*\]\(.*\)\s*\|\s*.*\|\s*.*\|\s*.*\|\s*\[chat\]\(.*\))$', re.I)
    for i, line in enumerate(lines):
        if course_name.lower() in line.lower() and pattern.search(line):
            if '✅' not in line:
                lines[i] = line.rstrip() + ' ✅\n'
                break

    with open(path, 'w', encoding='utf-8') as f:
        f.writelines(lines)

if __name__ == '__main__':
    if len(sys.argv) != 2:
        print('Usage: python mark_done.py "Course title substring"')
    else:
        tick_course(sys.argv[1])

Execute the script after finishing a course:

python mark_done.py "Systematic Program Design"

To generate a personal checklist of remaining courses, use this Bash script saved as list_pending.sh:

#!/usr/bin/env bash

# Prints every course line that does NOT contain a ✅

grep -E '\| \[[^\]]+\]\([^)]+\) \|' README.md | grep -v '✅' | nl

Run it to see your current queue:

bash list_pending.sh

These utilities transform the static Markdown into an interactive progress dashboard without external dependencies.

Summary

• The OSSU computer science curriculum follows a five-layer progression from prerequisites through a final capstone project, strictly adhering to CS 2013 guidelines documented in CURRICULAR_GUIDELINES.md.
• Core CS splits into eight sub-domains (Programming, Math, Tools, Systems, Theory, Security, Applications, Ethics) with dedicated coursepages/<topic>/README.md files for detailed course listings.
• Advanced CS offers elective specialization tracks in Programming, Systems, Theory, Information Security, and Math, activated only after Core completion.
• Progress tracking relies on community conventions: learners edit README.md to add ✅ marks beside completed courses, enabling simple Git-based version control of their academic journey.

Frequently Asked Questions

Is the OSSU computer science curriculum equivalent to a formal bachelor's degree?

The OSSU computer science curriculum covers the same core CS content required by the CS 2013 guidelines used by accreditation bodies, but it does not award academic credit or a diploma. It provides the knowledge equivalent minus general-education requirements, making it ideal for self-taught developers or degree-holders seeking CS fundamentals.

How long does it take to complete the entire OSSU CS curriculum?

Completion time varies by prior experience and study intensity. According to estimates in README.md, Core CS alone requires approximately 1,000 to 1,500 hours of study. Learners studying part-time (10-15 hours weekly) typically finish in 18 to 36 months, while full-time students may complete it in 9 to 12 months.

Can I skip courses or change the order within the OSSU curriculum?

While the repository recommends a specific sequence—especially completing Intro CS before Core CS—experienced learners can skip material they already master. However, the eight Core CS sub-domains assume cumulative knowledge; for example, Theory courses assume competency from Math and Programming prerequisites listed in their respective coursepages/ entries.

How do I contribute a new course or fix a broken link in the curriculum?

The ossu/computer-science repository is community-driven. Contributors should consult CONTRIBUTING.md for submission guidelines, then submit a pull request modifying the relevant README.md or coursepages/<topic>/README.md file. All additions must align with CS 2013 learning outcomes and link to permanently open-access resources.

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