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MRZ stands for Machine Readable Zone. It is the block of text at the bottom of passports, ID cards, and visas that scanners read in seconds.
ICAO 9303 defines the MRZ so every country reads the same fields in the same positions. That is why the MRZ looks similar no matter where a document is issued.
The MRZ is printed in OCR-B, a special font made for machine reading. Each character takes the same amount of space (like a typewriter), so scanners can split the line into equal boxes and read it reliably.
That fixed spacing is the reason the MRZ uses OCR-B even when the rest of the document uses a different font.
Common fields include document type, issuing country, document number, name, nationality, date of birth, sex, expiry date, and optional data.
Dates are encoded as YYMMDD (for example, 12 July 1942 becomes 420712).
Check digits are single numbers that help catch OCR or typing errors. Every MRZ uses the same calculation.
0-9 map to 0-9, A=10 through Z=35, and <=0.7, 3, 1 from left to right.mod 10; the remainder is the check digit.Example (date): 520727 -> sum 103 -> check digit 3.
Composite check digit uses L1[6-30] + L2[1-7] + L2[9-15] + L2[19-29].
Line 1: I<YTOD231458907<<<<<<<<<<<<<<<
Line 2: 3407127M9507122YTO<<<<<<<<<<<2
Line 3: ERIKSSON<<ANNA<MARIA<<<<<<<<<<Computed composite check digit: 2.
Composite check digit uses L2[1-10] + L2[14-20] + L2[22-35].
Line 2: HA672242<6YTO5802254M9601086<<<<<<<8Computed composite check digit: 8.
Composite check digit uses L2[1-10] + L2[14-20] + L2[22-43].
Line 2: HA672242<6YTO5802254M9601086<<<<<<<<<<<<<<08Computed composite check digit: 8.
Document number XK9305487 -> check digit 5; birth date 850221 -> 2; expiry 270314 -> 3.
Line 2: XK93054875BRA8502212F2703143R5T6U7V8W9<<<<<<Document number L23456789 -> check digit 7; birth date 920101 -> 7; expiry 270630 -> 6.
Line 2: L234567897DEU9201017F2706306QW12ER34Full SDK Suite gives teams one production-ready flow from document image to final MRZ decision.
It combines MRZ zone detection, OCR-B reading, and ICAO 9303 check-digit validation in one package, so your team avoids stitching separate components.
The workflow supports TD1, TD2, TD3, MRV-A, and MRV-B formats and returns structured output with clear status for each check.
Detects the MRZ area on passports, ID cards, and visas directly from full document images, including moderate rotation and uneven lighting.
Returns a normalized MRZ crop that can be passed directly into OCR reading.
Works with manual area selection fallback when operations teams need controlled overrides on edge cases.
Reads OCR-B MRZ characters into fixed-length text lines while preserving the exact layout needed for downstream validation.
Supports both two-line and three-line documents and prepares clean output for review, export, or integration into existing workflows.
Built for onboarding and back-office teams that need repeatable reading quality at scale.
Verifies ICAO 9303 check digits for document number, date of birth, expiry date, optional or personal number fields, and the composite checksum.
Returns a direct PASS/FAIL status for each check and shows expected values when a mismatch is found.
Gives operations teams a transparent validation trail and reduces rework caused by OCR or manual entry mistakes.