iReasoning MIB browser - Free MIB Browser

iReasoning MIB browser is a powerful and easy-to-use tool powered by iReasoning SNMP API . MIB browser is an indispensable tool for engineers to manage SNMP enabled network devices and applications. It allows users to load standard, proprietary MIBs, and even some mal-formed MIBs. It also allows them to issue SNMP requests to retrieve agent's data, or make changes to the agent. A built-in trap receiver can receive SNMP traps and handle trap storm.

Major features:

    Intuitive GUI
    Complete SNMPv1, v2c and v3 (USM and VACM) support
    Complete SNMPv3 USM support, including HMAC-MD5, HMAC-SHA, CBC-DES, CFB128-AES-128, CFB128-AES-192, CFB128-AES-256 (128-bit, 192-bit and 256-bit AES) algorithms
    Robust and powerful SMIv1/SMIv2 MIB parser
    IPv6 support
    Trap Receiver
    Trap Sender
    Log window to display application log and SNMP packets exchanged between browser and agents
    Port view (bandwidth utilization, error percentages) for network interface cards
    Switch port mapper for mapping switch ports
    Table view for MIB tables
    SNMPv3 USM user management (usmUserTable in SNMP-USER-BASED-SM-MIB)
    Device snapshot
    Cisco device snapshot
    Performance graph tool for monitoring of numerical OID values
    Ping and traceroute tools
    SNMP Agents Comparison
    Network discovery tool
    Runs on Windows, Mac OS X, Linux and other UNIX platforms

http://ireasoning.com/mibbrowser.shtml

Note: another free MIB browsers is getif, mibble