Bacterial endoglycosidases, particularly those from the glycoside hydrolase families GH18 and GH20, possess unique capabilities to cleave the glycosidic bonds within the chitobiose core of N-linked glycans. Enzymes like EndoE (from Enterococcus faecalis), EndoS (from Streptococcus pyogenes), and EndoF variants are widely utilized to deglycosylate IgG antibodies or remodel glycans on therapeutic proteins. Understanding the multi-modular structure of these enzymes and their specific interaction with complex or high-mannose glycans is essential for optimizing their use in biotechnology. High-affinity antibodies against these enzymes serve as pivotal reagents for monitoring enzyme expression, verifying purity during production, and detecting residual enzyme contamination in downstream processing.