Engineer's toolbox

Free, client-side utilities for the hex you stare at every day.

ATR, APDU, TLV, ASN.1, CBOR, ICCID, NDEF, SCP03 — all the parsers, decoders, and lookups that smart-card, secure-element, and telecom engineers reach for. No accounts. No ads. Nothing leaves your browser.

Need a searchable reference? Try the references section — APDU status words, EMV tags, AAGUIDs, COSE algorithms, X.509 OIDs, and more. Knowledge sharing belongs in the blog — including the EU Cyber Resilience Act series on CRA-aligned product security.

DECKAmbiSecure platform deck → REFS18 searchable reference databases → TIMELINEStandards evolution timelines → DOCSWebAuthn engineering reference → VIZPasskey flow visualizer →

Architecture & diagrams

SEQ

Sequence Diagram Generator

WebSequenceDiagrams syntax, SVG / PNG export, 7 built-in templates (FIDO2, SCP03, eSIM SGP.32, V2X PKI, UPI, banking MFA, device-identity lifecycle).

VIZ

Passkey Flow Visualizer

Interactive walk-through of WebAuthn registration and authentication.

Smart Card / JavaCard utilities

ATR

ATR Parser

Parse Answer-To-Reset bytes — TS, T0, TA/TB/TC/TD interface bytes, historical bytes, TCK.

APDU

APDU Parser

Decode CLA / INS / P1 / P2 / Lc / data / Le for Case 1–4, short and extended length.

TLV

TLV Parser

Walk BER-TLV, EMV TLV, and DGI-TLV trees with tag dictionary lookup.

APDU

APDU Builder

Build a valid ISO 7816-4 command APDU from CLA/INS/P1/P2/data/Le with live case detection and validation — or parse one back into fields.

ASN.1

ASN.1 Decoder

Decode BER/DER blobs into a clickable tree with X.509 OID lookup.

BER/DER

BER/DER Decoder

Same lower-level walker as the ASN.1 parser.

SW1/SW2 Lookup

Search status words by hex or phrase — ISO + GP + EMV + FIDO.

CAP

CAP File Inspector

Decode the 12 standard JavaCard CAP file components — opens the CAP Structure Explorer.

SCP03

SCP03 Helper

Educational AES-CMAC derivation of SCP03 session keys & cryptograms from static keys and challenges.

GP Status Reference

GlobalPlatform 2.3.1 card & application lifecycle states.

V2X / ITS PKI

1609.2

IEEE 1609.2 V2X Certificate Parser

Client-side COER decoder for V2X / ITS certificates. Hex, Base64, or PEM input. Standards references on every field row.

CHAIN

V2X Certificate Chain Validator

End-entity → intermediate → root. HashedId8 linkage via WebCrypto SHA-256. Structural-only.

Certificates & PKI

X.509

X.509 Certificate Viewer

Decode subject, issuer, validity, public key, all extensions.

PEM

PEM ↔ DER Converter

Convert certificates and keys between PEM and DER. Drag-and-drop, downloadable.

CSR

PKCS#10 CSR Decoder

Decode subject, public key, requested extensions, signature.

Cert Fingerprint Generator

SHA-1 / 256 / 384 / 512 of a cert’s DER. Web Crypto.

CHAIN

Certificate Chain Viewer

Walk a multi-cert PEM bundle; verify issuer→subject linkage.

B64

Base64 Cert Decoder

Auto-detect PEM / base64 / hex; emit DER + clean PEM.

PFX

PFX / PKCS#12 Inspector

Inspect bag types & encryption schemes inside a .pfx / .p12.

ASN.1

ASN.1 Parser

Walk any BER/DER tree with OID lookup. Used by every cert tool.

Encoding & conversion

ASCII

ASCII ↔ HEX

Bidirectional converter with multiple grouping styles.

HEX

HEX ↔ byte array

Convert across C / Java / Python / JS / escape-string formats.

B64

Base64

Encode / decode with URL-safe variant. UTF-8 friendly.

B32

Base32

Encode / decode Base32 & base32hex (RFC 4648). Optional padding, case-insensitive, TOTP-friendly.

UTF-8

UTF-8 inspector

Codepoints, byte counts, BOM detection, per-char view.

URL

URL encoder

Percent-encode / decode URLs and components. Space as %20 or +, malformed-input safe.

Crypto & security helpers

CRC

CRC calculator

70+ catalogue presets (CRC-8/16/32/64, CCITT, XMODEM, CRC-32C…) plus fully custom width/poly/init/refin/refout/xorout.

LRC

LRC calculator

XOR parity and 8/16-bit additive two’s-complement / modulo LRC, with STX/ETX framing and a step table.

SUM

Checksum

8/16/32-bit sums, one’s / two’s-complement, XOR, Fletcher-16/32, Adler-32, Internet (RFC 1071).

SHA

SHA hash generator

SHA-1 / 256 / 384 / 512 of text, hex, or a local file via Web Crypto. Hex & Base64 output.

RSA

RSA key formats

PKCS#1 / PKCS#8 / SPKI / PEM / JWK reference, plus an in-browser demo key generator (2048/3072/4096).

ECC

ECC curve reference

P-256/384/521, secp256k1, Brainpool, Ed25519/Ed448, X25519/X448 — sizes, uses, Web Crypto support.

eSIM, SIM & telecom

ICCID

ICCID Decoder

Issuer ID, country code, MII, individual account, and Luhn check. 19/20-digit aware.

IMSI

IMSI Decoder

MCC / MNC / MSIN breakdown with 2- or 3-digit MNC handling and a built-in MCC map.

7816

ISO/IEC 7816 Reference

APDU shape, CLA bits, common INS bytes — bookmarkable.

APDU Status Dictionary

Filterable full table — ISO 7816-4 + GP + EMV + FIDO.

EID

eUICC EID Decoder

Decode the 32-digit eSIM EID structure per GSMA SGP.02 / ITU-T E.118 and validate the check digit.

JSON / data utilities

JSON

JSON Bin Builder and Validator

Validate, format, minify, and save local JSON bins in your browser for API testing, static-site data, demos, and configuration examples.

JSON

JSON Formatter

Pretty-print, minify, and sort-key JSON with 2/4/tab indent and precise error location.

JSON

JSON Validator

Syntax validation with exact error location, plus a practical JSON Schema (2020-12 subset) checker.

CBOR

CBOR Parser

RFC 8949 decoder — FIDO/CTAP2 attestation, COSE keys. Opens the CBOR Decoder.

XML

XML Formatter

Format, minify, and well-formedness-check XML via the native DOMParser. No DTD/XXE processing.

NFC & DESFire

DESFire

DESFire Status Decoder

Look up DESFire response status bytes — OK, AUTH_ERROR, ADDITIONAL_FRAME, etc.

DESFire

DESFire Access-Rights Decoder

Decode the 16-bit access-rights word into Read / Write / R+W / ChangeAR.

NDEF

NDEF Decoder

URI, Text, Smart Poster, MIME, External (Android AAR) records.

UID

UID Analyzer

4 / 7 / 10-byte ISO 14443 Type A UIDs with manufacturer lookup.

ATS

ATS Parser

Decode ISO 14443-4 Answer-To-Select bytes.

14443

ISO/IEC 14443 Reference

Parts, Type A/B, anti-collision, I/R/S blocks. One-page reference.

FIDO / WebAuthn

REFERENCE

WebAuthn Reference

Developer-portal reference for registration / authentication / attestation, with copy-able code samples.

DEMO ↗

FIDO / WebAuthn Passwordless Authentication Demo

Interactive demo explaining passwordless authentication using public-key cryptography, authenticators, and phishing-resistant login flows. Opens the live AmbiSecure FIDO demo.

WebAuthn

WebAuthn Attestation Decoder

Walk attestationObject — fmt / attStmt / authData — with verification checklist.

WebAuthn

authenticatorData Parser

CBOR

CBOR Decoder

RFC 8949 walker. WebAuthn attestation, COSE keys, CTAP2 messages.

COSE

COSE Key Inspector

Decode COSE_Key (RFC 8152) — kty / alg / crv / x / y / n / e.

AAGUID

AAGUID Lookup

Curated offline directory of well-known FIDO authenticators.

WebAuthn

clientDataJSON Decoder

Decode type / challenge / origin / SHA-256 of the signed payload.

RP ID

RP ID / Origin Validator

WebAuthn §5.1.3 registrable-suffix rule, HTTPS, PSL constraints.

WebAuthn

Credential ID Inspector

Length, entropy, AAGUID-shaped prefix.

WebAuthn

Challenge Viewer / Generator

Inspect challenge length and entropy. Generate fresh 32-byte challenges with the platform CSPRNG.

B64URL

Base64URL Converter

RFC 4648 §5. The form WebAuthn / JOSE / CTAP2 use everywhere.

MDS

FIDO Metadata Explorer

Browse the curated AAGUID directory in metadata-style cards. Searchable by vendor / model.

FLOW

Passkey Flow Visualizer

Step-by-step walkthrough of registration and authentication ceremonies.

Smart-card developer tools

7816

ISO 7816-4 CLA Decoder

Walk the bit-fields of CLA — SM, chaining, channel, type.

BER

BER Length Visualizer

Decode and encode short / long / indefinite-form BER lengths.

EMV

EMV Tag Dictionary

Filterable directory of EMV Books 3, 4, and CL tags.

DESFire

Key Diversification Visualizer

Educational illustration of AES-CMAC diversification (NXP AN10922 / AV2).

SCP03

SCP03 Session Walkthrough

Educational annotation of the GP 2.3.1 secure-channel protocol.

CMAC

CMAC Length Calculator

Block count, padded length, and standard truncation for AES / TDES CMAC.

Secure Messaging Field Visualizer

Walk SM-wrapped APDU body — DOs 87 / 97 / 99 / 8E / 84.

SCRIPT

APDU Script Validator

Multi-line APDU script validation. Validation only — no execution.

CAP

JavaCard CAP Structure Explorer

Decode the 12 standard CAP file components. Header.cap walker.

ASN.1

ASN.1 Tree Explorer

Collapsible DER walker with OID lookup. PEM input accepted.

TLV

TLV Tree Visualizer

Visual companion to the TLV parser — collapsible nested tree with EMV tag lookup.

DESFire / Transit

DESFire

DESFire Status Decoder

OK, AUTH_ERROR, ADDITIONAL_FRAME, etc.

DESFire

Access-Rights Decoder

Decode the 16-bit access-rights word.

DESFire

File Settings Parser

Decode the GetFileSettings response per file type.

DESFire

Key Settings Interpreter

Decode the 2-byte GetKeySettings response.

TMAC

Transaction MAC Visualizer

EV2/EV3 TMAC field — TMC counter + TMV MAC.

14443

ISO 14443 Frame Explorer

REQA, WUPA, ATQA, SAK, RATS, I-block / R-block / S-block.

Misc developer utilities

BIN

Everything runs in your browser.

Every tool runs entirely inside your browser. No inputs leave the page, no accounts, no logging, no analytics on tool inputs — privacy-first by design.

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