Why Startups Choose C++: 3 Success Stories and Code

C++ is not just a language for enthusiasts, but the engine of unicorn startups

When we talk about modern startups, Python, JavaScript, or Go most often come to mind. But there is a whole class of projects that bet on C++ from the very beginning. Why? Because speed, memory control, and predictability are what distinguish a good product from a great one. In this article, we will analyze three real success stories of startups that built their business on C++, and look at the code that helped them take off.

Story 1: JetBrains — IDEs that write themselves

JetBrains is not just a company, it is a whole ecosystem of tools for developers. IntelliJ IDEA, CLion, PyCharm, ReSharper — all of them are written in C++ and Java. But why C++? The answer is simple: performance and working with low-level system calls.

The founders of JetBrains (Sergey Dmitriev, Evgeny Belyaev, and Valentin Kipyatkov) started with an idea: to make a smart code editor that understands context. To do this, they needed to analyze syntax in real time. In C++, this is easier to do than in Java because you can directly work with the AST (Abstract Syntax Tree) without unnecessary overhead.

Code example: fast token parser

Here is what a simple lexer in C++ that parses code into tokens might look like. These are exactly the components that underlie any code analyzer:

#include <iostream>\n#include <vector>\n#include <string>\n\nenum class TokenType {\n    KEYWORD, IDENTIFIER, NUMBER, OPERATOR, UNKNOWN\n};\n\nstruct Token {\n    TokenType type;\n    std::string value;\n};\n\nstd::vector<Token> tokenize(const std::string& source) {\n    std::vector<Token> tokens;\n    size_t i = 0;\n    while (i < source.size()) {\n        if (std::isalpha(source[i])) {\n            std::string ident;\n            while (i < source.size() && std::isalnum(source[i])) {\n                ident += source[i++];\n            }\n            tokens.push_back({TokenType::IDENTIFIER, ident});\n        } else if (std::isdigit(source[i])) {\n            std::string num;\n            while (i < source.size() && std::isdigit(source[i])) {\n                num += source[i++];\n            }\n            tokens.push_back({TokenType::NUMBER, num});\n        } else {\n            tokens.push_back({TokenType::OPERATOR, std::string(1, source[i++])});\n        }\n    }\n    return tokens;\n}\n\nint main() {\n    std::string code = "int x = 42 + y;";\n    auto tokens = tokenize(code);\n    for (const auto& t : tokens) {\n        std::cout << static_cast<int>(t.type) << ": " << t.value << std::endl;\n    }\n    return 0;\n}\n

This code is a simplified version of what CLion or ReSharper does. In C++, such parsers run tens of times faster than in interpreted languages. JetBrains chose C++ precisely for this speed — when an IDE "lags," the developer loses concentration. And in a startup, every second counts.

Story 2: Figma — how C++ saved web design

Figma is an online editor for interface design. It would seem like a web application, why use C++ here? But inside Figma, WebAssembly compiled from C++ is used. Why? Because rendering vector graphics in the browser via JavaScript is slow. But via C++, it's lightning fast.

Figma's founder, Dylan Field, previously worked at Microsoft on PowerPoint. He knew that complex graphics required a low-level approach. C++ allowed him to write his own 2D engine that runs directly in the browser via WebAssembly. The result — Figma became the standard for UI/UX design.

Code example: rendering a triangle in C++ in WebAssembly

#include <emscripten.h>\n#include <cmath>\n\nextern "C" {\n    EMSCRIPTEN_KEEPALIVE\n    void renderTriangle(int canvasWidth, int canvasHei