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Free IAB TCF String Decoder
Decode and analyse any IAB Transparency & Consent Framework string. Supports TCF v2.0, v2.2, and v2.3.
100% client-side - your TC String never leaves your browser.
Decoded TC String Results
Understanding TCF
What is a TC String?
The IAB Transparency & Consent Framework uses compact, encoded strings to store consent and legitimate interest preferences across the digital advertising ecosystem.
Core Segment
Contains CMP information, creation timestamps, consent language, TCF policy version, and the vendor consent/legitimate interest bitfields.
Purposes & Vendors
11 standard purposes, 2 special features, and per-vendor consent and legitimate interest bits covering the entire IAB Global Vendor List.
Additional Segments
Disclosed Vendors (required in v2.3), Allowed Vendors (deprecated), and Publisher TC for publisher-specific purpose consent and custom purposes.
Reference Guide
TCF Purpose & Special Feature Reference
All 11 standard purposes and 2 special features defined by the IAB Transparency & Consent Framework.
Standard Purposes
| ID | Purpose | Description |
|---|---|---|
| 1 | Store and/or access information on a device | Cookies, device or similar online identifiers can be stored or accessed on your device for the purposes presented to you. |
| 2 | Select basic ads | Ads can be shown to you based on the content you're viewing, the app you're using, your approximate location, or your device type. |
| 3 | Create a personalised ads profile | A profile can be built about you and your interests to show personalised ads that are relevant to you. |
| 4 | Select personalised ads | Personalised ads can be shown to you based on a profile about you. |
| 5 | Create a personalised content profile | A profile can be built about you and your interests to show personalised content that is relevant to you. |
| 6 | Select personalised content | Personalised content can be shown to you based on a profile about you. |
| 7 | Measure ad performance | The performance and effectiveness of ads you see or interact with can be measured. |
| 8 | Measure content performance | The performance and effectiveness of content you see or interact with can be measured. |
| 9 | Apply market research to generate audience insights | Market research can be used to learn more about the audiences who visit sites/apps and view ads. |
| 10 | Develop and improve products | Your data can be used to improve existing systems and software, and to develop new products. |
| 11 | Use limited data to select content | Content can be selected based on limited data, such as the content you're viewing or your device type. |
Special Features
| ID | Special Feature | Description |
|---|---|---|
| 1 | Use precise geolocation data | Your precise geolocation data can be used in support of one or more purposes. |
| 2 | Actively scan device characteristics for identification | Your device can be identified based on a scan of your device's unique combination of characteristics. |
FAQ
Frequently Asked Questions
What is an IAB TC String?
A TC (Transparency & Consent) String is a standardised, base64url-encoded string created by the IAB Europe Transparency & Consent Framework. It stores a user's consent and legitimate interest preferences for data processing purposes and vendors in the digital advertising ecosystem. CMPs generate this string when users interact with a cookie consent banner.
What is the difference between TCF v2.0, v2.2, and v2.3?
TCF v2.0 was the initial version with 10 purposes and basic vendor consent. v2.2 added Purpose 11 ("Use limited data to select content"), tightened legitimate interest requirements, and introduced the useNonStandardTexts field. v2.3, mandatory from February 2026, makes the Disclosed Vendors segment required (previously optional), preventing "ghost vendors" from processing data without being shown in the CMP UI.
What are the segments in a TC String?
A TC String contains up to 4 segments separated by dots: (1) the Core segment (always present) with consent defaults, purposes, and vendor consent/LI; (2) the Disclosed Vendors segment listing vendors shown in the CMP UI; (3) the Allowed Vendors segment (deprecated in v2.3); and (4) the Publisher TC segment with publisher-specific purpose consent and custom purposes.
What is the Disclosed Vendors segment?
The Disclosed Vendors segment is a bitfield indicating which vendors were displayed to the user in the CMP's consent interface. In TCF v2.3, this segment is mandatory. Vendors must check that their ID has a 1 bit in this segment before processing personal data - even under legitimate interest. A 0 means the vendor was not disclosed, and processing would violate GDPR transparency requirements.
How do I find the TC String on my website?
You can find the TC String by: (1) opening your browser's developer console and running
__tcfapi('getTCData', 2, function(data) { console.log(data.tcString); }), (2) checking the euconsent-v2 cookie value, or (3) using a browser extension like "Consent Mode Inspector" or "CMP Auditor". The TC String is also passed in ad requests as the gdpr_consent parameter.What does this decoder check?
This decoder parses the raw binary structure of a TC String and displays: the TCF version, CMP information, timestamps, consent language, all 11 purposes with consent and legitimate interest status, 2 special feature opt-ins, full vendor consent and legitimate interest lists (resolved to vendor names via the IAB Global Vendor List), publisher restrictions, disclosed vendors, and the Publisher TC segment if present.
Need IAB TCF compliance for your website?
Kukie.io is working towards full IAB TCF v2.3 support with automatic TC String generation.