AI API Pricing in 2026: What You Actually Pay for GPT-5.5, Claude Opus, Gemini, and 20+ Models

A prompt that costs $30 on GPT-5.5 costs $0.28 on DeepSeek V4 Flash. That's a 100x difference — and it's real. If you're building on AI APIs, the pricing landscape in 2026 is more fragmented than ever. Four major providers, twenty-plus models, and pricing tiers that include cache reads, cache writes, batch discounts, promotional pricing, and hidden thresholds. I built a token cost calculator to make sense of it. This is the pricing data behind it. All prices are per million tokens (MTok) in US...