JKS Viewer Online
Open and inspect Java KeyStore (JKS), PKCS12, PFX and JCEKS files directly in your browser.
KEYSTORE FILE UPLOAD (.JKS, .P12, .PFX, .JCEKS)
How to Use
Open JKS Files Online
The ToolMono JKS Viewer Online enables developers, DevOps engineers, Android mobile developers, and security auditors to open JKS online without installing the Java Development Kit (JDK) or configuring command-line tools. Simply upload a .jks or .keystore file, enter the password if required, and instantly inspect all stored aliases, cryptographic certificates, public keys, and certificate fingerprints directly in your web browser.
Unlike desktop utilities like KeyStore Explorer that require full Java runtime installation, ToolMono runs 100% locally in your browser memory using HTML5 FileReader and WebCrypto APIs. Your keystore binary files and passwords are never uploaded, transmitted, or logged on remote servers, providing maximum data confidentiality for private enterprise certificates and Android release keys.
All binary stream decoding, ASN.1 parsing, and SHA-256 fingerprint calculations execute locally in browser memory. Your keystore and passwords never leave your device.
Open and inspect Java KeyStore (.jks), PKCS#12 (.p12, .pfx), and .jceks files instantly without JRE or keytool setup.
Instantly extract colon-delimited and hex SHA-256 / SHA-1 certificate fingerprints formatted for Google Play Console, Firebase, and Google Cloud OAuth credentials.
JKS File Viewer
A JKS file viewer is a dedicated tool for inspecting the internal structure and cryptographic assets stored inside a Java KeyStore file. When you view JKS files or inspect JKS files with ToolMono, the viewer decodes and displays:
Entry Aliases & Entry Types
Identifies whether each alias is a PrivateKeyEntry (private key with certificate chain) or a TrustedCertificateEntry (public root/intermediate CA).
Subject & Issuer Distinguished Names
Parses Common Name (CN), Organization (O), Organizational Unit (OU), Country (C), and full Distinguished Name strings for owner and issuing CA.
Serial Number & Version
Displays the unique certificate serial number in hexadecimal and integer formats alongside the X.509 version standard (v3).
Validity Dates & Expiry Countdown
Evaluates Not Before and Not After UTC dates, calculating exact remaining days and flagging expired or expiring certificates in real time.
Public Key & Signature Algorithms
Inspects public key type (RSA, EC), key modulus bit size (2048-bit, 4096-bit), and signature schemes (SHA256withRSA, SHA384withECDSA).
Cryptographic Fingerprints (SHA-256 & SHA-1)
Computes standard colon-delimited and raw hex fingerprints for mobile app distribution, Firebase, and API authorization.
Java Keystore Viewer
A Java Keystore (JKS) is a storage facility for cryptographic keys and trusted digital certificates used across the Java Virtual Machine (JVM) runtime ecosystem. Introduced in Java 1.2 by Sun Microsystems, the JKS binary format organizes private keys and certificates into uniquely named aliases.
Over time, Java keystore implementations have evolved into multiple distinct container formats:
PrivateKeyEntry (Key Pair & Chain)
Contains an encrypted private key accompanied by an X.509 certificate chain (leaf certificate, intermediate CAs, and root CA). Used for server SSL/TLS handshake authentication (Tomcat, Spring Boot, Netty), mutual TLS (mTLS), and Android APK/AAB package signing.
TrustedCertificateEntry (Truststore)
Contains a single public X.509 digital certificate representing a trusted Certificate Authority (CA) or remote party. Used by JVM truststores (such as the standard cacerts file in $JAVA_HOME/lib/security/cacerts) to validate outbound HTTPS and TLS connections.
View Certificates Inside a JKS File
Every entry in a Java KeyStore contains one or more X.509 certificates. For TrustedCertificateEntry items, the keystore holds a single public certificate. For PrivateKeyEntry items, the keystore stores a certificate chain tracing trust back to a root authority.
Our jks certificate viewer parses and displays full certificate details in both human-readable format and standard ASCII PEM format (-----BEGIN CERTIFICATE-----). You can inspect every attribute, verify certificate validity dates, check key lengths, and click 'Export PEM' to save individual certificates to your local filesystem.
Need to decode standalone PEM certificates or certificate signing requests? Use our companion PEM Certificate Decoder to inspect SAN extensions, verify leaf certificates, and calculate certificate hashes.
Get SHA-256 Fingerprint from a JKS File
Extracting the SHA-256 fingerprint from a JKS file is a routine requirement for Android developers and cloud engineers. Android app signing requires configuring SHA-256 certificate fingerprints across multiple platforms:
- Google Play Console: App Integrity and Play App Signing certificate verification.
- Firebase Console: Phone Authentication, Google Sign-In, Dynamic Links, and SafetyNet/Play Integrity verification.
- Google Cloud Console: OAuth 2.0 Client IDs for Android applications (matching package name + SHA-256 fingerprint).
- Android SDK & API Integrations: Third-party SDK authentication (e.g., Google Maps API, payment gateways).
- Upload your Android
release.keystore,upload-keystore.jks, ordebug.keystore. - Enter the keystore password (default for Android debug keystores is
android). - Select your signing key alias (e.g.,
uploadorandroiddebugkey). - In the certificate details panel, locate the SHA-256 Fingerprint section.
- Click 'Copy SHA-256' to copy the standard colon-delimited hex fingerprint directly to your clipboard.
4E:7B:9A:12:F3:6C:54:8D:90:1A:BC:DE:F1:23:45:67:89:AB:CD:EF:01:23:45:67:89:AB:CD:EF:01:23:45:67
Supported Keystore Formats
ToolMono JKS Viewer natively parses the following binary and container formats directly in the client runtime:
| Format | Common Extension | Magic Bytes / Header | Description & Use Cases |
|---|---|---|---|
| JKS | .jks | 0xFEEDFEED | Traditional Java KeyStore format. Default in Java 1.2 through Java 8. |
| PKCS#12 | .p12, .pfx | 0x30 0x82 (ASN.1 DER) | Industry-standard certificate/key container (RFC 7292). Default format in Java 9+. |
| JCEKS | .jceks | 0xCECECECE | Java Cryptography Extension KeyStore for storing symmetric keys with Triple-DES PBE. |
| Java Keystore | .keystore | Variable (JKS / PKCS12) | Common filename convention for Android release/debug signing keys and Tomcat SSL certs. |
JKS vs PKCS12 vs JCEKS vs Java Truststore (cacerts)
Understanding the distinction between keystore formats helps you select the optimal container for your infrastructure:
JKS (Java KeyStore)
Proprietary binary format legacy to Java. Default in Java 8 and earlier. Uses proprietary SHA-1 password-based integrity checks.
PKCS12 (.p12 / .pfx)
Standardized, language-agnostic container (RFC 7292). Default in Java 9+ and Spring Boot 3+. Supported across OpenSSL, Windows, iOS, and macOS.
JCEKS
Java Cryptography Extension KeyStore. Uses stronger Triple-DES encryption to store symmetric keys (AES, DES) alongside certificates.
cacerts Truststore
The standard JVM truststore containing root Certificate Authorities. Located in $JAVA_HOME/lib/security/cacerts with default password changeit.
How to Open a JKS File
Follow this simple guide to open and inspect any Java Keystore file in your browser:
- Select your .jks or .keystore file: Drag and drop your keystore file into the upload zone above or click to browse files.
- Enter password if required: Enter the store password (use
changeitfor Java cacerts, orandroidfor Android debug keystores). - Click 'Inspect Keystore': The parser instantly decrypts and indexes all aliases and certificate entries.
- Review keystore entries: View the summary dashboard showing total entries, private keys, and trusted certificates.
- Select an alias: Inspect Subject/Issuer DNs, validity range, serial numbers, and public key specs.
- Copy fingerprints or export PEM: Copy the SHA-256 fingerprint for Google Play / Firebase, or click 'Export PEM' to download certificates.
Inspect JKS with Java keytool
If you have the Java Development Kit (JDK) installed locally, you can also inspect Java Keystores using the command-line keytool utility:
keytool -list -v -keystore keystore.jks
keytool -list -v -keystore keystore.jks -storepass changeit
keytool -exportcert -alias myalias -keystore keystore.jks -rfc -file cert.pem
Why use ToolMono instead of keytool? ToolMono's online JKS viewer requires no JDK installation, works on any device (including mobile and locked-down developer laptops), eliminates the risk of exposing sensitive passwords in shell history (.bash_history), and provides instant visual expiry auditing and one-click fingerprint copying.
Common JKS Errors & Fixes
When inspecting, converting, or deploying Java Keystore (.jks) and PKCS#12 (.p12) archives, developers frequently encounter runtime exceptions. Below are common errors and how to resolve them:
java.io.IOException: Invalid keystore format
Cause: Magic byte mismatch. Occurs when a PKCS#12 / PFX binary archive (beginning with ASN.1 DER sequence 0x30 0x82) is opened using the legacy Sun JKS engine (0xFE 0xED 0xFE 0xED magic header), or when opening a JKS file on Java 9+ without specifying -storetype JKS.
ToolMono Fix: ToolMono automatically reads the binary magic header at the byte level in-browser, dynamically streaming the payload to the matching parser with zero CLI configuration.
java.io.IOException: Keystore was tampered with, or password was incorrect
Cause: JDK keytool verifies a mandatory SHA-1 HMAC integrity checksum across the entire file before loading aliases, refusing to open even public certificates if the password is unknown.
ToolMono Fix: Bypasses strict file-level HMAC locks for public certificate entries, allowing you to extract public SANs, expiry timestamps, and Android SHA-256 fingerprints even with forgotten passwords.
AlgorithmId unsupported: PBEWithSHAAnd3KeyTripleDES-CBC
Cause: Modern JVMs (JDK 17+) and OpenSSL 3.0 disable legacy Password-Based Encryption (PBE) algorithms (such as 3DES, RC2, and SHA-1) by default in security policies.
ToolMono Fix: Uses an isolated client-side WebCrypto cryptographic engine to safely unpack legacy PBES1/PBES2 keybags without modifying system-wide JVM security configs.
java.security.UnrecoverableKeyException: Cannot recover key
Cause: In legacy JKS stores, the private key entry password differs from the keystore container password.
ToolMono Fix: Clearly distinguishes between keystore store-level passphrases and individual private key aliases in the structured inspector dashboard.
Frequently Asked Questions
References & Cryptographic Standards
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