Open Arsenal

Infrastructure for Transparent, Auditable Advertising.

OpenBid Ledger is an open source specification for transparent, auditable digital advertising auctions. It provides a modular framework in which business bids, auction activity, pricing decisions, advertising delivery, billing, and settlement records are permanently preserved in an immutable ledger. The specification is designed to eliminate hidden auction activity and prevent a hosting service from manipulating the bidding process or altering the historical record of an auction.

OpenBid Ledger requires bidding to be visible within the applicable auction environment. Bids cannot be hidden, selectively disclosed, suppressed, altered, deleted, backdated, reordered, or replaced. Every bid receives a unique identifier, timestamp, and permanent ledger record, while rejected, withdrawn, expired, winning, and losing bids remain part of the auction history. Administrative actions, configuration changes, rule changes, and other actions capable of affecting an auction are also recorded, creating a complete and independently auditable history.

The specification uses a modular architecture with separate components for auction execution, bidding, immutable records, verification, auditing, billing, settlement, advertisers, publishers, and advertising inventory. It provides dedicated Cost Per Click (CPC) and Cost Per Impression Unit (CPIU) functionality. CPC auctions calculate charges from validated clicks, while CPIU auctions calculate charges from validated impressions using an Impression Unit defined by the hosting service. The hosting service must disclose the Impression Unit before bidding begins, and the applicable definition becomes part of the immutable auction record.

OpenBid Ledger is designed to make the hosting service accountable without giving it unilateral control over the auction record. Cryptographic verification, immutable event histories, audit records, published rules, and independently verifiable auction results allow advertisers, publishers, and auditors to determine what occurred during an auction. The architecture can support independent hosts, interoperable implementations, and additional modules without requiring participants to trust a single operator. OpenBid Ledger provides infrastructure for transparent, auditable advertising.

This specification is licensed under AGPL-3.0+ and is free to use with required Section 7 attribution. Attribution-free deployment is available through a Specification Branding License, with fees based on use and deployment scope.