Why I Built FastCSV-C: Making CSV Handling Easy Across Languages

For years, I had nightmares handling CSV in both Python and PHP—across many real-world projects. Sure, there are packages out there. But they’re often slow, leak memory, choke on edge cases, or silently corrupt data with encoding quirks.

I didn’t want to keep rewriting the same CSV handling logic over and over.
I wanted something faster, safer, and simpler—a library I could trust, and plug into any runtime without dealing with high-level overhead.

That’s exactly why I built FastCSV-C:
A fast, memory-safe CSV library written in C, designed to be embedded in PHP, Python, Go, or any language that can talk to C.

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The Problem: CSV Is Simple—Until It’s Not

CSV should be easy. But in practice, it’s messy:

• Newlines in quoted fields
• Files with broken UTF-8 or mixed delimiters
• Huge files that eat memory or crash halfway through
• Language-specific quirks that break cross-platform portability

Even worse, the overhead of working in high-level languages (like PHP or Python) can be a deal-breaker. You’re stuck managing logic in the app layer, which slows everything down—especially when reading or writing many small rows.

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The Vision: A Core Engine That Works Everywhere

My goal was clear:

✅ Fast: Stream massive files with low memory usage
✅ Safe: No leaks, no corrupt output, no guesswork
✅ Embeddable: Use it from any language—PHP, Python, Go, etc.
✅ Standard-aware: Handle the weirdness of real-world CSV, while sticking close to RFC 4180

I didn’t want to build “yet another CSV parser”—I wanted to move the logic closer to the runtime, so app code stays clean and fast.

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Why Not Rust or Zig?

Good question. I actually started there. I wrote a whole post about it (Why I Tried Writing a PHP Extension in Rust or Zig), but the short version:

⚠️ FFI overhead kills performance for small, frequent operations
⚠️ Build systems can be tricky to integrate with ecosystems like PHP, which have their own mature (and sometimes rigid) extension-building workflows.
⚠️ Memory safety isn’t free when you cross the language boundary
⚠️ Ironically, C was faster and simpler when used well

This isn’t a post about why I didn’t use Zig or Rust—that story is told elsewhere.
This post is about why I returned to C and what I learned building something usable, fast, and clean across language boundaries.

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Introducing FastCSV-C

FastCSV-C is a minimal, efficient CSV library written in C, with clean APIs and custom memory management via arenas (memory pools). It’s designed to:

🧠 Prevent memory leaks with scoped arenas
⚡ Stream data efficiently without wasting memory
🔌 Connect easily to any language with C FFI
📚 Stay documented and readable (docs are improving, promise!)

Example Usage

#include "csv_writer.h"
#include "arena.h"
#include "csv_config.h"

int main() {
    Arena arena;
    arena_create(&arena, 1024 * 1024); // 1MB arena

    CSVConfig *config = csv_config_new(&arena);
    csv_config_set_path(config, "output.csv");
    csv_config_set_delimiter(config, ',');

    char *headers[] = {"name", "age", "city"};
    CSVWriter *writer = NULL;
    csv_writer_init(&writer, config, headers, 3, &arena);

    char *row1[] = {"Alice", "30", "New York"};
    csv_writer_write_record(writer, row1, 3);

    char *row2[] = {"Bob Smith", "25", "Los Angeles"};
    csv_writer_write_record(writer, row2, 3);

    csv_writer_free(writer);
    arena_destroy(&arena);
    return 0;
}

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Made for Extensions: PHP, Python, and More

Because FastCSV-C is written in plain, modern C, it can be integrated into almost any language runtime with minimal overhead.

The PHP extension I’m working on (stay tuned for a separate post) is just a thin layer with no speed loss—and similar wrappers are easy for other languages too.

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What I Learned

🧠 High-level code shouldn’t carry low-level burden: CSV logic belongs in the engine, not in scripts
🧱 C is powerful when used safely: With arenas and clean APIs, it’s not scary
🔧 Make the API feel native: Keep it simple and ergonomic to wrap
🚫 Avoid overengineering: No macros, no templates, just a clean core

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Try It Out

• 📦 GitHub: FastCSV-C
• 📚 Documentation
• 🚀 Use it in your language of choice, or build your own binding

If you’re tired of fighting CSV in your app logic—especially across multiple platforms—FastCSV-C is made for you. It’s not magic. It’s just clean C code, doing its job well.

“I built the CSV library I wish I had years ago—maybe now, others won’t have to suffer the same pain.”