FB2 file (FB2) stores data in the FB2 format. NUMBERS file (NUMBERS) stores data in the NUMBERS format. This conversion changes the file's encoding, compression method, and supported feature set. Metadata such as creation date and embedded colour profiles is preserved where the target format supports it. The result is a standard NUMBERS file readable by any compatible application. 1converter handles FB2-to-NUMBERS conversion server-side: files are uploaded over HTTPS, processed on isolated cloud infrastructure, and the converted output is available for download for 24 hours before automatic deletion. No account is required for standard conversions.