And one more practical clarification: Is it better to submit such volumes to the tool as one big .txt file for the whole project or split into separate segments for upload? Would the report freeze if I submitted a large list of pages for the audit all at once?

As an SEO specialist with experience in mass checks of large e-commerce projects, I can assure you that there are no problems with this. The service can handle large files because packages can contain up to 1,000,000 links. The service is designed for large lists and can handle heavy loads easily. From my experience, we uploaded entire sitemaps as .txt files to this index checker, and the bot processed everything stably without any failures. Some time ago, we bought a bulk token package for a big audit. It was budget-friendly at $0.015 per check and fully covered the task. If you want to test the speed of file parsing, you get 50 free checks after registering — just try uploading a small file. How many URLs do you plan to include in the first wave of the audit? Will you split the list by category, or will you upload everything in one file?