Blog
Mert Özen's blog posts on software development, backend, frontend, and DevOps.
The Evolution of LLM APIs: From Completions to Tool Calling, Structured Outputs and MCP
The evolution of LLM APIs with verified dates, from the first text-continuing API to the chat format, from function calling to JSON mode and structured outputs, from reasoning parameters to the Model Context Protocol and agents. We see which example in the series each step maps to, and at the end of the series we build a bridge to the next AI series.
LLMs from 2023 to Today: Open-Weight Models, Long Context and Reasoning
A summary of the LLM world from GPT-4 to today with verified dates: the rise of open-weight models with Llama, Mistral, Qwen and Gemma, the context window growing from 2,048 tokens to a million, models that read images, and the reasoning models that came with o1 and DeepSeek-R1. We also discuss the difference between open-weight and open source, and why we give no model ranking.
From the Transformer to ChatGPT: The Birth of LLMs (2017–2022)
The steps that made today's LLMs possible, from the 2017 "Attention Is All You Need" paper to the launch of ChatGPT: the Transformer, pre-training with GPT-1 and BERT, GPT-2's staged release, scaling laws and GPT-3, InstructGPT and RLHF. We see which concept in the series each step is the root of and what it changed for developers.