Jaehyun Cho (@jonhisking)

@jonhiskingSeoul, South KoreaJoined September 2026

I'm an indie developer from South Korea. I build TokenSave (tokensave.app), a free, private calculator for AI tokens and API costs. It runs entirely in your browser and supports 34 languages. I like measuring how different languages tokenize, and how much that costs.

@jonhiskingSeoul, South KoreaJoined September 2026

Jaehyun Cho

About

Available for

Jaehyun Cho's blogs

Recently published

I counted tokens for the same data in 7 formats. Pretty JSON costs 3× CSV

ChatGPT Pro 100 vs 200 vs 500: Every Tier Costs the Same per Unit of Usage

I measured GPT token costs in 10 Indian languages: Malayalam dropped from 10× to 1.85×

Jaehyun Cho

About

Available for

Jaehyun Cho's blogs

Recently published

I counted tokens for the same data in 7 formats. Pretty JSON costs 3× CSV

ChatGPT Pro 100 vs 200 vs 500: Every Tier Costs the Same per Unit of Usage

I measured GPT token costs in 10 Indian languages: Malayalam dropped from 10× to 1.85×

Jaehyun Cho

About

Available for

Jaehyun Cho's blogs

Recently published

I counted tokens for the same data in 7 formats. Pretty JSON costs 3× CSV

ChatGPT Pro 100 vs 200 vs 500: Every Tier Costs the Same per Unit of Usage

I measured GPT token costs in 10 Indian languages: Malayalam dropped from 10× to 1.85×

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Jaehyun Cho

About

Available for

Jaehyun Cho's blogs

Recently published

I counted tokens for the same data in 7 formats. Pretty JSON costs 3× CSV

ChatGPT Pro 100 vs 200 vs 500: Every Tier Costs the Same per Unit of Usage

I measured GPT token costs in 10 Indian languages: Malayalam dropped from 10× to 1.85×