Freelancer cuts LLM API costs 40x by switching from GPT-4o to DeepSeek V4 Flash

A freelance developer was paying around $275 per month on OpenAI's GPT-4o to run a client support chatbot processing roughly 65 million tokens monthly. After spending a weekend benchmarking seven model providers, he migrated to DeepSeek V4 Flash, available via a global API at $0.18 per million input tokens and $0.25 per million output tokens — compared to GPT-4o's $2.50 and $10.00 respectively. The switch brought his monthly bill for that single client down to approximately $11.25, saving over $260 per month. He found output quality comparable to GPT-4o for about 95% of tasks, including JSON extraction, function calling, and streaming, with the migration taking roughly 20 minutes. He notes the alternative falls short only for OpenAI-specific features such as the Assistants API, fine-tuning, and text-to-speech.