If you're looking for an image-to-text converter that can handle a group of images, ChatPhoto is definitely worth a look. It's got a batch mode for groups of images, so you can get useful information out of a group of photos with a single command. The system also has multilingual support and a chat interface for interactive Q&A, so it's good for generating captions for social media and websites.
Another good option is Describe Picture. This AI-based system can accept groups of prompts for description, summarization and translation. It's got features like Image Content Extraction and Intelligent Image Recognition to give you detailed descriptions of complex scenes and textures. It's geared for anyone from content creators to developers, and has an interface that makes image processing easy.
If you're looking to boost your social media presence, Image To Caption is an AI-based caption generator. It's geared for single-image captions, but it can help you boost engagement and expand your audience on Instagram, Facebook and Twitter.
Last, you might want to consider Describe Picture and ChatPhoto depending on your needs. If you want a system with a lot of different image processing tools, Describe Picture is worth a look. If you want a simple image-to-text conversion with batch mode, ChatPhoto is a good choice.