In MOW’s view, the W3C’s recently published attribution specification raises a number of competition issues, both in general and with specific regard to the W3C’s own Antitrust Policy. The W3C management team need to rule it out of scope and close down the work.
But don’t take it from us. As an experiment to see the clear competition issues this new specification presents we fed it to some of the leading AI’s with the following prompt:
“Analyse the documents https://w3c.github.io/attribution/ and the https://www.w3.org/policies/antitrust-2024/ and then identify any competition issues associated with the Attribution document.”
Their outputs are below and the conclusion seems to be unanimous – there are serious questions for the W3C to answer on this topic.
Co-Pilot (Microsoft)
Here’s an analysis of potential competition issues associated with the W3C Attribution specification, based on its content and W3C’s antitrust policy:
1. Centralization of Aggregation Services
- The Attribution API allows websites to select an aggregation service from a list approved by the user-agent (browser). This creates a risk that dominant browser vendors (e.g., Google, Apple, Mozilla) could:
- Restrict the list to their own or affiliated services.
- Impose technical or contractual conditions that disadvantage independent providers.
- This could lead to foreclosure of competition in the market for aggregation services and reinforce browser dominance. [w3c.github.io]
2. Market Power of Browser Vendors
- The API is implemented at the browser level, giving major browser vendors control over:
- Which attribution methods are supported.
- How privacy budgets and aggregation rules are enforced.
- If browsers favor their own advertising ecosystems (e.g., Google Ads for Chrome), this could discriminate against rival ad-tech firms, raising self-preferencing concerns similar to those highlighted in regulatory debates. [movementfo…penweb.com]
3. Barriers to Entry for Smaller Ad-Tech Firms
- The specification introduces complex privacy-preserving mechanisms (e.g., differential privacy, global budgets), which require significant technical resources to implement.
- Smaller firms may struggle to comply, while large incumbents can absorb these costs, potentially entrenching existing market leaders. [arxiv.org]
4. Risk of Coordinated Behavior
- W3C working groups include competitors (Google, Meta, Mozilla), and discussions about attribution standards could:
- Influence pricing or technical choices indirectly.
- Create industry-wide alignment that limits innovation or alternative approaches.
- W3C’s antitrust policy warns that such collaboration must avoid anticompetitive agreements or exclusionary practices. [w3.org]
5. Impact on Third-Party Advertising
- The Attribution API is designed to reduce cross-site tracking, which aligns with privacy goals but:
- Could favor first-party data holders (large platforms) over third-party advertisers.
- This shift may reduce competition in digital advertising markets, as smaller players rely more on cross-site attribution. [movementfo…penweb.com]
6. Patent and Licensing Risks
- The specification operates under W3C’s Patent Policy, but if essential patents are controlled by dominant firms, they could:
- Limit access through restrictive licensing.
- Create royalty or exclusivity barriers for competitors. [w3c.github.io]
Summary
The main competition concerns are:
- Gatekeeping by browsers over aggregation services.
- Self-preferencing by dominant vendors.
- Barriers to entry for smaller firms due to technical complexity.
- Risk of coordinated standard-setting reducing competitive diversity.
- Shift toward first-party dominance in advertising markets.
Gemini (Google & Apple)
Competition concerns related to the W3C Attribution document center on the potential for dominant browser developers to self-preference their advertising solutions, potentially disadvantaging smaller competitors and restricting innovation in the ad technology market. Critics worry the proposed standards could centralize data access or processing, creating an uneven playing field. W3C’s antitrust policy aims to mitigate these risks through open processes and encouraging royalty-free intellectual property. Read more about the concerns at W3C.
Claude (Anthropic)
I’ll fetch and analyze both documents to identify any potential competition issues.
Fetched Attribution Level 1
github.io
Fetched Antitrust and competition policy – 2024 version
w3.org
Based on my analysis of both documents, I’ve identified several potential competition issues with the Attribution document when viewed through the lens of the W3C Antitrust and Competition Policy:
Potential Competition Issues
1. Aggregation Service Provider Selection and Market Access
The Attribution API requires sites to select from browser-supported aggregation services, with the browser determining which services are available through the aggregationServices attribute github. This creates potential competition concerns:
- Market gatekeeping: Browser vendors control which aggregation service providers can participate, potentially excluding competitors or favoring certain providers
- Barriers to entry: New aggregation service providers must be approved/whitelisted by each browser vendor, creating significant market entry barriers
- The W3C policy prohibits “excluding any person or entity from any given market or from competition” w3
2. Protocol Standardization Limiting Competition
The specification defines only two aggregation protocols: “dap-15-histogram” (DAP-based MPC) and “tee-00” (TEE-based) github. This limitation could:
- Restrict competition to only those service providers who can implement these specific protocols
- Favor larger companies with resources to implement complex cryptographic protocols
- Create technical barriers that could be seen as “excluding any person or entity from any given market” w3
3. Intermediary Market Power and SSP/DSP Control
The specification explicitly accommodates intermediaries like Supply-Side Platforms (SSPs) and Demand-Side Platforms (DSPs), allowing them to call the API from iframes and have their site identity saved with impressions github. This could:
- Entrench existing ad-tech intermediaries who are first to implement
- Create data advantages for early adopters that disadvantage late entrants
- Potentially facilitate coordination between competitors in the ad-tech space
4. Implementation-Defined Values Creating Competitive Disparities
The specification includes numerous “implementation-defined” parameters including maximum histogram size, maximum lookback periods, and privacy budget limits github. This creates risks that:
- Different browser implementations could favor certain business models over others
- Competitors might discuss or coordinate “appropriate levels” of these parameters w3, which the antitrust policy prohibits
- Dominant browsers could set parameters that disadvantage smaller competitors in the attribution service market
5. Privacy Budget as Competitive Tool
The privacy budget mechanism allocates limited measurement capacity per site per epoch, with “last-write-wins for concurrent updates” github. This could:
- Enable larger players to exhaust privacy budgets and deny measurement to smaller competitors
- Create first-mover advantages in accessing measurement data within each epoch
- Potentially be used strategically to harm competitors’ measurement capabilities
6. Coordination Risks Among Ad-Tech Competitors
The specification’s development and implementation necessarily involves:
- Direct competitors (Google, Meta, Amazon, etc.) in the advertising technology space
- Potential for discussing “individual company marketing plans, strategies, or market division” including “customers to be targeted” w3 under the guise of technical standardization
- Risk of coordinating on measurement methodologies that could affect competitive behavior
7. Proprietary Configuration Requirements
Sites must obtain and configure HPKE encryption keys and DAP task configurations from specific aggregation services github, which:
- Creates switching costs that lock sites into particular service providers
- Could enable anti-competitive bundling practices
- May facilitate prohibited discussions of “specific contractual arrangements, or terms of customers or suppliers” w3
Recommendations for Mitigation
To address these concerns while maintaining the W3C’s commitment to open and fair deliberations leading to consensus-based decisions w3, the working group should consider:
- Establishing clear, objective criteria for aggregation service approval
- Creating an open registration process for new aggregation protocols
- Defining minimum interoperability requirements to prevent lock-in
- Standardizing implementation-defined parameters or providing clear guidance
- Documenting how the specification ensures fair competition among service providers
- Regular antitrust compliance reviews of working group discussions
Perplexity
The Attribution Level 1 document introduces a privacy-preserving API for measuring advertising effectiveness, while the W3C Antitrust and competition policy sets the guidelines to prevent anti-competitive behavior in standards development. Several competition issues may arise from implementing the Attribution API, considering both documents:
Aggregation Service Competition
The Attribution API depends on aggregation services to process conversion data and generate differentially-private metrics. Sites must choose an aggregation service from those supported by browsers, and browsers have the discretion to support any set of aggregation services. If major browser vendors restrict their supported aggregation services to those they control or have commercial relationships with, smaller independent providers could be excluded, risking monopolistic practices and reduced competition. This scenario would violate the antitrust principle of discouraging market exclusion and promoting interoperability.
Choice and Interoperability
Interoperability, a core W3C value, encourages competition by allowing easy substitution between products or services. The Attribution API’s flexibility for sites to select among supported aggregation services is positive for interoperability, provided browsers implement support transparently. If browsers or advertising platforms create technical, commercial, or process barriers to entry for new aggregation services, it limits competition and could lead to dominance by a few providers, which competition policy warns against.
Privacy as a Competitive Factor
The use of differential privacy and aggregation could favor services able to deliver strong privacy guarantees while providing useful analytics. If certain aggregation services have unique technical capabilities or proprietary protocols not available to others, it could create technical lock-in or advantage, counter to W3C’s open standards and antitrust principles.
Delegation and Inclusion
The Attribution API enables intermediaries such as supply-side platforms (SSPs) or demand-side platforms (DSPs) to participate, but permissions are policy-controlled. If a browser or platform selectively enables or disables access to these APIs by certain intermediaries, it could result in arbitrary exclusion from the market, violating antitrust guidance that competitively sensitive decisions should not be made except following a transparent, non-discriminatory process.
Voluntary and Open Participation
Both documents emphasize voluntary adoption and broad participation. If the Attribution API’s implementation leads to de facto requirements for publishers or advertisers to use specific aggregation services or proprietary features, it could breach W3C’s competition policy and potentially attract regulatory scrutiny.
| Potential Issue | Description | Relevant Policy Principle |
| Aggregation Service Gatekeeping | Limiting supported services in browsers; exclusion of independents. | Market exclusion, interoperability |
| Technical Barriers to Entry | Use of proprietary protocols/technical lock-in for aggregation services. | Open access, royalty-free standards |
| Arbitrary API Access Control | Selective enabling/disabling of API for intermediaries. | Nondiscriminatory inclusion |
| Forced Commercial Relationships | Requirement to use certain services/platforms for access. | Voluntary implementation |
Summary Table
Careful attention is needed to ensure the Attribution API fosters competition, remains open, and avoids gatekeeping or monopolistic practices in line with W3C’s antitrust and competition policies.
MOW’s Summary
So it seems that the AIs agree with us – the W3C’s plans are deeply flawed within the terms of their own policies. If we wanted to summarise these objections we would argue as follows:
The W3C Attribution API, designed as a “privacy” improving replacement for personal data tracking, when exchanging event data among different organizations, introduces structural control points that can carry significant antitrust implications. The conduct risks below align with recognized forms of competitive harm under modern competition law frameworks.
| Category of Anticompetitive Conduct | Summary of Concern | Competitive Effect | Relevant W3C Policy Principle |
| 1. Discriminatory Self‑Preferencing Conduct by Browser Gatekeepers | Browser vendors that both design and implement the Attribution API may favor their own aggregation or advertising services through technical design, default configurations, or selective support. | Distorts competitive neutrality in the ad‑tech ecosystem, reinforcing vertically integrated browser platforms such as Chrome or Safari. | Neutral design, nondiscriminatory inclusion, and open interoperability. |
| 2. Exclusionary Conduct Restricts Innovation and Market Access | Browser control over the list of approved aggregation services restricts smaller or unaffiliated firms from participation. | Forecloses competition from independent providers. | Open access, transparent approval processes, and avoidance of market exclusion. |
| 3. Collusive Behavior in Standard‑Setting | Collaboration within W3C working groups risks coordinated alignment among dominant browser vendors on protocols and standards that unfairly dictate market outcomes. | Enables soft coordination and dampens innovation, violating the antitrust norm against concerted practices. | Compliance with antitrust obligations during technical standardization. |
| 4. Preferential Treatment of First‑Party Platforms in B2B Markets | The API’s design advantages platforms that already hold direct consumer relationships by reducing data available to B2B rivals, regardless of risks of data collected or communicated. | Shifts market power to dominant first‑party platforms and weakens independent B2B rival solution providers. | Promotion of competitive diversity and prevention of market foreclosure. |
Brief Narrative Summary
The move from open interoperability to browser‑controlled attribution systems concentrates economic and technical power within a small number of browser vendors. Regulators should monitor implementation to ensure non‑discriminatory service access, prevent coordination among dominant platform competitors, and preserve fair competition between first‑ and third‑party participants. Uniform application of interoperability principles will be critical to maintain open competition.