Why finding it matters
9 in 10
radicalised extremists sentenced in England and Wales in 2019 to 2021 were radicalised at least partly online.
Source: HM Prison and Probation Service, 2022.
Terrorist Content Discovery Index
If terrorist content can be found in five minutes, detection is falling short.
We measure how easily terrorist content can be found online. Platforms report how much terrorist content they remove. No standard measure shows how easily it can still be found.
The Terrorist Content Discovery Index (TCDI) scores every find on one ten-level scale, on every platform and over time.
The ten levels of discoverability
Every find is scored by how hard it was to find.
A lower level means the content was easier to find, which is a more serious failure of detection.
Detection failures
Under 5 minKeyword search
Under 5 minAltered keywords
Under 5 minLogos and flags
Under 5 minKnown propaganda
Moderate evasion
Under 30 minCoded language
1 to 2 hoursLinked accounts
2 to 4 hoursCross-platform links
Effective concealment
1 to 2 daysClosed groups
Several daysDisguised content
Sustained workDeep investigation
Proposed benchmark: basic automation should catch levels 1 to 4. Content found mainly at levels 8 to 10 shows effective detection.
How easy, not how much
Findable
A prevalence figure says how much there is. TCDI measures the effort it takes to find it with public tools.
The index records how each find was made, so it shows where detection falls short, platform by platform.
The five-minute test
What can a basic public search find in five minutes?
The test counts how much terrorist content basic public searches find on a platform within five minutes. It uses only the platform's public search, so it measures what any user could reach.
5 minutesfor each test
Public searchthe tools any user has
How it works
Every find records how it was found.
Together, the finds show where detection falls short.
Find
Our analysts and trusted flaggers record finds in daily work, and run five-minute tests on major platforms.
Record
Each find gets its level, the time it took, the platform and the content type.
Combine
With how long removal takes, the records show how each platform performs over time.
What it produces
Levels by platform
How hard terrorist content is to find on each service.
Trends
Whether discoverability is rising or falling.
Comparisons
Where each platform is stronger or weaker than others.
Removal speed
Whether easy-to-find content is removed faster or slower.
Who it serves
One scale that regulators, platforms and researchers can all check.
Regulators
Evidence to test platforms' detection claims under UK and EU online safety law.
Governments
A shared scale, so countries can compare results and align expectations.
Platforms
A published method that shows where detection misses content.
Researchers
One way to record finds, so evidence from many organisations adds up.
What we ask
What we ask of each group.
Regulators
Review the method, then recognise it as an evidence standard in guidance.
Platforms
Review the method before it is published, and tell us where it is wrong.
Funders
Fund regular assessments across major platforms, with public reporting.
Trusted flaggers and researchers
Record your finds on the same ten levels.
Scope and fairness. TCDI covers content from groups on UK, EU, US or UN terrorism designation lists, and material produced by terrorist attackers or glorifying their attacks. The method will be published for review before any results, and platforms are told their results before anything is published.
What comes next
From a published method to the first annual report.
- 1
Phase 1
Method published for review
- 2
Phase 2
Pilot tests across major platforms
- 3
Phase 3
Public launch
- 4
Phase 4
First annual report on discoverability
Get in touch
Help us shape the index before it launches.
Talk to us about the method, a pilot or a partnership.
Or use the form at techagainstterrorism.org/contact-us.
