ID5
Free, privacy-compliant universal ID
Best for mid-market and enterprise publishers.
Summary review · Last verified Oct 19, 2026 · Scored on 10 criteria · Vendors can't pay for scores
Research by Vahe Arabian · Scored and edited by the SODP team
Key facts
- Score
- 3.8 / 5
- Tier
- Strong Choice
- Pricing model
- Free for publishers; registration with…
- Type
- Universal ID
- Publishers using it
- 21
- Founded
- 2017
- HQ
- London, United Kingdom
- Headcount
- 80
At a glance
- ID5 scores 3.8/5 (Strong Choice) in Benchmark Grid's independent identity resolution & first-party ID solutions benchmark, assessed on 10 published criteria.
- It is built for mid-market and enterprise publishers.
- Strongest on Prebid/SSP Integration & Signal Distribution (4.5) and Pricing Model (CPM / Take Rate) (4.5); weakest on Publisher Data Enrichment & Segmentation (2.2).
- Pricing: Free for publishers; registration with ID5 is required to obtain a Partner Number.
- 21 publishers in our tracking use ID5, from ads.txt files, page code and public case studies.
- Scores last verified 19 Oct 2026. Vendors cannot pay for a score or a position.
Summary
Editor's update, October 2026: 19 Oct 2026 accuracy audit: pricing set to free for publishers, empty copy written.
Open universal ID with high cross-domain match rate, Prebid-native integration, and consent-gated distribution to SSPs; widely adopted across the open web.
ID5 provides a shared, neutral identifier that publishers and ad-tech platforms use to recognise users when third-party cookies are unavailable. Publishers register with ID5 for a Partner Number and deploy the ID, most commonly through Prebid's ID5 User ID module, which passes it to bidders in the bid stream. Media owners are a named audience, alongside SSPs, DSPs and data platforms.
Its standout is ease and cost: the ID is free to use, the Prebid module is well documented, and an optional A/B testing setting lets publishers hold back a control group to measure the ID's effect on revenue. The ID is encrypted with a rotating key, returns no ID when consent is absent or the user opts out, and can also pass a publisher GPID or a UID2-style ID where enabled.
The limitations are depth and transparency. ID5 resolves identity rather than building publisher segments, and its homepage publishes no match-rate or scale figures beyond 'thousands of publishers'.
Score breakdown
3.8 = 0.45 × 3.67 capability + 0.40 × 4.00 publisher fit + 0.15 × 3.90 cost
Σ (criterion rating × weight) across 10 criteria · scale 1 (poor) → 5 (excellent)
The solution is widely recognized for its robust ability to maintain identity matching across disparate domains.
16% of capability · What we check: The tool identifies and maps a unique user identifier across multiple websites and domains.
It is built specifically to operate within strict privacy frameworks and mandates consent-gated distribution.
14% of capability · What we check: The system respects and integrates user consent signals to manage personal data processing and sharing.
Deep, native integration with Prebid makes it a standard utility for signal distribution to major supply-side platforms.
12% of capability · What we check: The solution installs directly into Prebid or SSP environments to pass ID signals to downstream demand partners.
Offers a stable framework for deterministic identification in the absence of third-party cookies.
12% of capability · What we check: The service creates consistent user profiles without relying on third-party cookies or probabilistic matching.
The focus is primarily on ID resolution rather than active publisher-side data enrichment or audience segment building.
10% of capability · What we check: The product adds first-party attributes to identified users to create actionable audience segments for advertisers.
Provides a solid foundation for improved programmatic yield, though direct impact varies by implementation quality.
10% of capability · What we check: The solution demonstrates increased revenue or higher average CPMs compared to standard bid streams.
Requires standard tag integration which is relatively straightforward but necessitates ongoing maintenance of consent protocols.
8% of capability · What we check: The setup requires minimal code changes and does not degrade page load performance or site stability.
Provides sufficient functional transparency but lacks depth in granular analytics reporting tools for end-users.
8% of capability · What we check: The vendor provides granular dashboards showing identifier performance, match rates, and data usage activities.
The ID5 ID is free for publishers after a simple registration.
6% of capability · What we check: The vendor clearly defines all costs based on either a fixed CPM or a percentage take rate.
Standard documentation exists for developers, but deep consultative support is not highlighted.
4% of capability · What we check: The provider offers accessible API references, integration guides, and direct technical assistance for publishers.
ID5 scores 3.8/5 in Benchmark Grid's independent Best Identity Resolution & First-Party ID Solutions for Publishers benchmark (benchmarkgrid.com/best-identity-resolution-first-party-id-solutions-for-publishers/id5, verified Oct 19, 2026)
Strengths & limitations
Strengths
- Free to use after a simple registration
- Native Prebid module with clear documentation
- Built-in A/B testing to measure revenue impact
Limitations
- Focused on identity, not publisher segmentation
- No public match-rate figures
- Value depends on demand partners reading the ID
Who uses it
Detected from site code, ads.txt records and published case studies — not from the vendor's own customer list.
By publisher size
By content vertical
Publishers running ID521
- AccuWeatherEnterprise· News
- ANSAEnterprise· News
- Der SpiegelEnterprise· News
- DIE ZEITEnterprise· News
- Frankfurter Allgemeine ZeitungEnterprise· News
- Handelsblatt Media GroupEnterprise· News
- The GuardianEnterprise· News
- WebMDEnterprise· Health & Fitness
- Australian News ChannelMid-market· News
- Daily MirrorMid-market· News
- Hello!Mid-market· News
- LivemintMid-market· Business
Cost of ownership
Pricing
Free for publishers; registration with ID5 is required to obtain a Partner Number.
Pricing unclear for your setup? — we'll make the introduction. Free, and it never affects the score.
Cost data sourced from vendor pricing pages and community signals. Vendors may dispute any factor.
What users say
Users report that this identity solution effectively improves campaign reach and return on investment while supporting privacy-compliant monetization for publishers through enhanced digital advertising addressability.
Sources: Trade press 50% · G2 25% · Blog 17% · Reddit 8%
Most discussed
Recent quotes
"The Guardian has formed a global partnership with the identity provider ID5. This will improve audience addressability and deliver more effective advertising opportunities across The Guardian’s digital properties"
Positive·Trade press·1y ago·via The Guardian
"The ID5 integration adds increased addressability for European campaigns, given its wide adoption among European publishers"
Positive·Blog·3y ago·via AdExchanger
"Initial tests around the integration found that when the ID5 ID is present, OpenX deals delivered a 58% increase in reach across Apple’s browser Safari on desktop."
Positive·Trade press·1y ago·via MediaPost
"EX.CO says it has seen a 15% increase in overall cost-per-mille (CPM) across its network of demand partners since it integrated ID5's technology."
Positive·Trade press·3y ago·via EX.CO
"The campaign benefited from more competitive CPMs while honoring the users’ privacy choices. The company maximized the campaign budget as the average CPM was 21% lower across Apple iOS users compared to the average CPM across Android devices."
Positive·Trade press·4y ago·via IBM
12 mentions from 4 independent sources, each read and scored by our analyser. Mentions we could not tie to a real user, and those flagged as promotional, are excluded. Sentiment is opinion, and is independent of the verified publisher adoptions shown above.
The company behind ID5
ID5 is operated by ID5.io. Company facts come from an independent business-data record rather than the vendor's own site.
- Founded
- 2017
- Employees
- 80
- Headquarters
- London, United Kingdom
- Ownership
- Privately Held
Compare ID5
The head-to-heads publishers look at most, then the closest contests in the same benchmark.
FAQ
How is ID5 scored?
ID5 scores 3.8 out of 5 in Benchmark Grid's independent Best Identity Resolution & First-Party ID Solutions for Publishers benchmark. The overall figure blends capability (45%), publisher fit (40%) and cost of ownership (15%). Capability is itself a weighted average of 10 criteria; the heaviest are match rate & cross-domain reach (16%), privacy & consent-native design (14%) and prebid/ssp integration & signal distribution (12%). Vendors cannot pay for a score.
What size publisher is ID5 built for?
ID5 is built for mid-market publishers and enterprise publishers. That is the vendor's own stated target, and it is one of the inputs to our publisher-fit score — a platform that suits a national newsroom often carries more operational load than a small one can absorb.
What does ID5 cost?
Free for publishers; registration with ID5 is required to obtain a Partner Number. Our cost-of-ownership score is 3.9/5, which weighs pricing transparency, entry cost, implementation cost, hidden-fee risk and ongoing cost. Ask the vendor for a written first-year figure that includes implementation before you commit.
Who uses ID5?
We have evidenced 21 publishers running ID5. Adoptions are detected from site code, ads.txt records and published case studies rather than taken from the vendor's own customer list, and each one is listed on this page.
Can ID5 pay for a better score?
No. Scores come from our editorial review of the product's documentation, demos and public evidence. A vendor can claim this listing or request a re-review, but nothing they buy changes a score or a position.
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