Q4 is known as the ‘golden quarter’ for retailers, thanks to the multiple holidays that see shopping surge. But for those in the engine rooms of advertising, it also presents significant challenges as brands encourage people to buy, buy, buy and the bidstream fills and overflows with excess media trading traffic. Here, we provide programmatic practitioners on both the buy and sell side with a straightforward checklist to manage the issue through bidstream hygiene - an important practice all year round, but particularly as we approach peak season.
Bidstream hygiene: Essential good practice in the ‘unforgiving’ season for giving
Although eagerly awaited by brands and retailers, Q4 is a volatile period in the programmatic ecosystem, with various pressure points displaying stress symptoms as the seasonal dynamics introduce more volume, complexity and risk.
For a start, traffic spikes as adspend surges and the bidstream, flooded with requests from DSPs and SSPs, experiences dramatically heavier query volumes. There are also more duplicate auctions as SSPs tap into the spending rush, repackaging and reselling inventory across multiple exchanges. Additional partners are often brought onboard, which extends the supply path, and increases the number of ‘hops’ (with a hop defined as each intermediary that an ad impression passes through on its way between the publisher and advertiser). Media trading becomes less efficient, while discernible value is limited.
And while it may be spending season on the part of consumers and advertisers, this doesn’t equate to publishers having more inventory; the resulting imbalance in supply and demand leads to the bidstream becoming bloated.
This crowded bidstream (with many bid requests being redundant or irrelevant) makes timeouts more likely because it is harder for DSPs to respond fast enough to meet SSP time limits (set to keep auctions efficient); the DSP therefore loses the opportunity to bid on the inventory that is available.
At the same time, the high volumes provide a happy hunting ground for bad actors; malvertisers are ready to exploit the seasonal spikes, with tactics such as redirects, fake deals and phishing creatives all embedded into legitimate ad flows. Security filters, their workload increased, struggle to stay ahead without adding to the latency risk.
The overall result of this multi-faceted bidstream stress is higher infrastructure costs (as DSPs and SSPs navigate the processing of an excess of bid requests), latency and missed bids - at a time when programmatic performance needs to be wearing its best party outfit.
While there are solutions and advice on offer, the choice can seem overwhelming. We’ve put together a practical, checklist-based antidote to promote ‘bidstream hygiene’ - the set of practices that keep bid requests accurate, authorised, deduplicated, privacy-compliant, and useful.
Pipe-cleaning: A practical checklist for buy and sell side
1. Foundational authorisation and transparency
The IAB Tech Lab’s transparency standards, created to help prevent programmatic ad fraud, are also important for bidstream hygiene.
Hosted on a publisher’s website, ads.txt lists all the companies authorised to sell that publisher’s inventory; app-ads.txt extends this to mobile apps, CTV apps and other non-web environments. Sellers.json shows who is selling or reselling inventory through SSPs and exchanges, and schain spotlights every intermediary of the supply path from buyer to seller.
A check that ads.txt and app-ads.txt listings tally with those of sellers.json confirms which of the entities selling inventory are authorised to do so. Deprecated sellers and resellers (those that don’t feature on both lists) should be removed, and all unauthorised non-CTV traffic blocked (an action that BidSwitch would take immediately).
Checking schain hops, introducing caps where possible (a task that BidSwitch can carry out) and removing any unknown links, allows the supply chain to be managed and unnecessary complexity removed.
Finally, verifying that the domain field - or bundle ID for in-app inventory - in a bid request contains the canonical root domain of the publisher’s website ensures that impressions come from legitimate publishers or apps; these checks protect buyers from bidding on spoofed or misconfigured sources.
2. Signal quality and addressability
Incomplete, inconsistent or low-value data cluttering the bidstream leads to inefficiency. Improving signal quality and addressability is therefore a key part of bidstream hygiene, turning raw bid data into a clean efficient marketplace; DSPs can bid with confidence, SSPs can demonstrate value and, overall, fewer resources are wasted.
A complete bidstream means the OpenRTB standard protocol is fully populated with the core information required by a DSP when deciding on whether to bid (device type, geo location of the user; details of the app or site where the ad will appear, etc - all of which must be compliant with data privacy laws); without these details, DSPs may reject the bid request altogether, bid on it less aggressively, or parse invalid data.
Legitimate and privacy-compliant identity signals, with non-standard and pseudo-IDs removed, improve efficiency and reduce data noise. Established, interoperable signals (such as hashed email addresses, publisher login IDs, and third-party IDs - RampID, UID2, ID5,
etc) deployed across the complete supply chain when legally possible help DSPs make better, compliant bidding decisions.
Leveraging the standardised identifiers Global Placement ID (GPID) and Transaction ID (TID) maintains transparency and traceability across all platforms within the programmatic supply chain. Considered best practice in bidstream hygiene, this ensures clarity and operational efficiency.
For CTV, bidstream cleanliness relies on accurate app / channel metadata (the information about the CTV environment), authentic bundle IDs and clear Identifiers for Advertising (IFAs), the CTV equivalent of a device ID (although this can only be used if the user hasn’t opted out of tracking).
3. Deduplication and volume control
A key culprit in bidstream bloat is duplicate or redundant bid requests for the same impression, along with excess traffic that adds no value. Here we look at some core cleanup techniques.
A single ad impression sent through multiple SSPs, exchanges or resellers appears many times in the bidstream, leading DSPs to register several separate opportunities and bid accordingly. Deduping auctions by reducing duplicate bid requests from header bidding and wrappers, while consolidating overlapping supply paths is key element in bidstream hygiene.
Bid requests can be over-filled with programmatic deals (private marketplaces, programmatic guaranteed, preferred) if the publisher or SSP wants to make inventory available through multiple buying options. A single impression might go to a DSP on repeat or accompanied by a long list of unrelated deals. Limiting each impression to only valid, applicable deals reduces noise, improves efficiency and prevents wasted spend.
Controlling the number of bid requests needs to be done strategically, rather than throttling traffic blindly. QPS controls allow traffic volume to be managed and optimized so that SSPs match available impressions with the buyers most likely to bid while suppressing traffic to those that haven’t historically bid on that inventory type. Rather than sending bids to every possible DSP endpoint, routing intelligently cuts noise, saves resources and delivers a cleaner, higher quality bidstream.
4. Safety and quality
Ensuring that malicious or non-compliant creatives don’t enter the ecosystem is key to keeping the bidstream clean. Quality assurance (QA) for creatives verifies that ads served are safe, compliant and display properly, thereby reducing malvertising risks such as ads carrying malware, auto-redirects, or non-compliant content.
This requires checks that upstream players actively scan all creatives for malware and policy violations, ideally using automated scanning tools, and that suspicious creatives are blocked (or at least quarantined) before they reach the platform in question. It also calls for a response plan to be in place should a bad creative slip through, including who to contact, how to escalate and a defined process to immediately block or pause offending campaigns.
It's key to evaluate the quality and legitimacy of supply, specifically to control Made for Advertising (MFA) sites, which are synonymous with low-value inventory, and fraudulent activity in the form of invalid traffic (IVT). Players should each have a clearly defined set of criteria or scoring rules against which supply partners are systematically audited, along with agreed cutoff points for when a source should be blocked or deprioritized. The resulting automated or policy-based filtering keeps the bidstream clean and efficient.
Finally, it’s important to control how long to wait for bids and responses, striking a balance between the risk of missing impressions and poor viewer experiences. The maximum amount of time set for each step of the bidding process (the latency budget) needs to be realistic, based on what partners can deliver. For CTV it’s about confirming the length of ad pods (or ad breaks) and how many ads it can contain, as well as whether timeouts are for the whole pod, or per slot (to prevent a slow bidder impacting the whole break).
5. Privacy and compliance
User consent signals (under regulations such as CCPA, GDPR, etc.) must be accurate, consistent and unaltered as they travel through the supply chain.
Preferences (such as whether a user has agreed to tracking, personalization, etc.) are encoded in a consent string — usually Transparency & Consent Framework (TCF) for Europe, or Global Privacy Platform (GPP) for other regions including the US and Canada; these communicate the user’s privacy choices to everyone in the ad transaction.
Verification that the string is in the right place, is accurate, and remains unchanged as it passes through intermediaries is needed. In other words, there must be proof that no partner in the chain is tampering with the user’s consent signal to make more inventory appear eligible for targeting. Any bid request with a malformed consent string, missing consent data or conflicting privacy signals should be rejected.
Programmatic platforms operate globally, but privacy and data-use laws differ by region; they therefore need to be ready to handle local privacy regulations and signals automatically within the bidstream. This requires identifying the user’s geolocation and automatically applying the right privacy enforcement logic. More than that, ad delivery systems should be tested to ensure they enforce these rules, for example by simulating bid requests from different locations to check that they honor the regulations in that territory.
Breaking it down: Role-based actions
So far we’ve looked at general good practice to ensure bidstream hygiene. But what are the specifics that each side of the buying equation can carry out?
For SSPs
- Cross-check the data in sellers.json and ads.txt / app-ads.txt to ensure that every seller and reseller in their ecosystem is legitimate. This mapping also enables stale or inactive resellers to be purged, reducing unnecessary hops and minimizing bidstream bloat.
- Enforce accurate domain and bundle ID fields to prevent spoofing and misrepresentation; rejecting malformed or missing values keeps the bidstream clean, trustworthy, and efficient.
- Run a ‘hop count’ report to identify unnecessarily long or redundant supply paths that inflate the bidstream with extra intermediaries. Detecting and reducing excessive hops improves transparency, cuts latency and costs, and delivers cleaner, more direct routes.
- Apply traffic shaping to control the volume and quality of bid requests going to buyers, thereby reducing noise, lowering infrastructure costs and improving win rates. Collaborating with partners (such as BidSwitch) ensures traffic shaping systems interact with each other in a way that prevents over-throttling or duplication and makes the most valuable traffic available to demand partners.
For DSPs
- Tune filters to prefer direct supply paths so that they buy inventory from the most transparent and efficient supply routes; this reduces the risk of fraud, minimizes intermediary fees and cuts latency.
- Set strict bundle and domain validation to ensure the source of every impression is legitimate and verifiable. Domain spoofing and misrepresented app traffic is prevented and wasted spend on invalid inventory reduced.
- Monitor win-rate by supply path and ID to identify the routes and sellers that deliver the most efficient and high-quality outcomes. This level of performance tracking helps to detect broken or low-value supply paths so that they can be avoided, thereby maintaining a cleaner bidstream.
- Collaborate with supply partners to trim ‘noisy’ routes that generate redundant or low-quality. Streamlining these paths reduces bidstream clutter, lowers infrastructure costs and results in cleaner, more efficient supply chains.
Checks and balances: proof points for a streamlined bidstream
Having undertaken the checklists above (and taken remedial action as necessary), how can buy and sell side demonstrate that the bidstream is cleaner? The following metrics all provide key insight:
- QPS versus win-rate: A reduction in QPS without lower win-rates indicates that excess or low-quality bid requests have been removed - i.e. that efficiency has improved without performance being sacrificed.
- Bid / request ratio: An increase in the ratio of bids to requests shows that buyers are responding to a higher proportion of cleaner, more relevant bid opportunities.
- Timeouts: Fewer timeouts demonstrates that DSPs are receiving leaner, better-structured traffic in time for bids to be actioned successfully.
- Invalid / malformed fields: Lower numbers confirm that data quality has improved, and that it follows the correct format and structure.
- Average hop count: Reducing the hop count reflects that the supply path is more direct and transparent, with fewer redundant intermediaries.
- Authorized, direct paths: An increased proportion of these routes means that more bid requests are coming from verified publisher relationships, i.e. that the SSP sells inventory directly for the publisher, rather than through resellers.
BidSwitch: A helping hand when it comes to hygiene
With its neutral middleware role, BidSwitch makes media trading easy and efficient, and partners have the following tools to hand to help them when it comes to bidstream hygiene.
SmartSwitch traffic shaping only forwards bid requests that are likely to win the auction, thereby reducing unnecessary volume and, with that, infrastructure costs. (For SSPs that leverage their own traffic shaping technologies, BidSwitch offers a learning logic exchange to ensure SmartSwitch complements any other traffic shaping being done.) LiteSwitch enables these traffic shaping policies to be extended beyond BidSwitch-mediated pipes.
BidSwitch also provides path and duplication analytics to show hop distributions, duplicate patterns, malformed fields, and ID pass-through gaps, all of which assist with identifying potential issues. And our neutral best-practice advisory provides impartial guidance to help buyers and sellers follow shared standards - such as hop caps, field validation, and consent pass-through - for cleaner, more transparent trading.
Better business for the holiday season
It’s in the interests of all media trading partners to ensure the bidstream is as clean and streamlined as possible.
This checklist has been designed to show that running a 30-minute hygiene audit is straightforward. From there reports on hops, supply paths and malformed fields should be shared with key partners and guardrails agreed.
For a traffic-shaping review to make your bidstream as clean as possible in time for the critical Q4 season, contact your BidSwitch account team today.