ads.txt Generator for Seller Lines and Variables

How to use it

Type one seller record per line in Seller records, one per line, with the fields separated by commas. Replace the sample lines with your own.
Fill in CONTACT, SUBDOMAIN, OWNERDOMAIN or MANAGERDOMAIN only if you need them.
Read the note under the result for any line that was left out, and correct that line.
Copy the ads.txt file, or download it, and upload it to your site as ads.txt.

The format

IAB Tech Lab's ads.txt 1.1 specification describes a data record as four comma-separated fields: the ad system's domain, the publisher account ID, the account type and an optional certification authority ID. The account type is DIRECT or RESELLER, and the specification reads it case-insensitively (section 3.3). The fourth field may be left out (section 4.2).

A variable is written as NAME=value. The specification names CONTACT, SUBDOMAIN, OWNERDOMAIN, MANAGERDOMAIN and INVENTORYPARTNERDOMAIN (section 3.5.1). A line that starts with # is a comment and is ignored (section 3.2).

What the tool checks

The ad system's domain is a domain name: labels of letters, digits and hyphens with dots between them, and no protocol, no path and no underscore.
The account ID and the certification ID contain no spaces, tabs or commas. The specification says such characters should be URL-encoded (section 3.4.2), so the tool asks you to remove them instead.
A record has three or four fields, and the account type is DIRECT or RESELLER.
SUBDOMAIN, OWNERDOMAIN and MANAGERDOMAIN are domain names. MANAGERDOMAIN may be followed by a comma and a two-letter country code.

What the tool does not check

Whether an account ID is the one the ad system issued to you. Copy it exactly from the ad system's account page, because only the ad system can confirm it.
Whether an ad system accepts your line, or whether a seller approves your site. The file lists your sellers; each one decides how it reads its own line.

Worked example: two sellers and a contact

You sell through adnetwork.example with the publisher account 12345 as a DIRECT seller, and through exchange.example with the account 67890 as a RESELLER. You add the contact [email protected].

The tool writes the two records in order, then the variable, one line each. The record for adnetwork.example keeps its fourth field, the certification ID a1b2c3d4.

Line in the file
adnetwork.example, 12345, DIRECT, a1b2c3d4
exchange.example, 67890, RESELLER
[email protected]

Frequently asked questions

What do DIRECT and RESELLER mean?

DIRECT means the ad system sells your inventory itself, and RESELLER means it passes your inventory on to another seller. The IAB Tech Lab specification defines both (section 3.3). Use the value your ad system gives you for your account.

Where do I find my account ID?

It comes from the publisher account of the ad system, or from the seller's own instructions. The tool cannot check it, so copy it exactly, with the same capitals and digits.

Why is a line left out of the file?

The line has too few or too many fields, a domain that is not a domain name, an account type other than DIRECT or RESELLER, or a space inside the account ID or the certification ID. The note under the result gives the line number.

Does this file make my site approved by the ad systems?

No. The file lists the sellers you have, in the format the specification describes. Each ad system decides how it reads your line, and whether you may sell through it.

Why are the variables written after the records?

The specification does not set an order. Any line with the form VARIABLE=value is read as a variable, wherever it stands (section 3.5). The tool writes the variables after the records to keep the file easy to read.

Can I keep comments in the file?

The specification allows them: a line that starts with # is a comment and is ignored (section 3.2). The tool skips # lines in the box and does not copy them to the file, so keep your notes outside the file.

Sources

Figures and text last checked on Tuesday, November 10, 2026.

Result