OlmOCR is an open-source OCR tool designed to extract plain text from PDFs effectively while running locally on Nvidia GPUs. It offers features such as recognizing handwriting and maintaining the correct reading order in output, especially for multi-column PDFs. Users have noted its limitations, including the inability to extract text from diagrams and potential inaccuracies in output. Comparisons to other tools, like Tesseract OCR, highlight the ongoing evolution of OCR technology and the impact of AI on improving traditional methods.