TierDiffBot

TierDiff records how the free tiers of developer services, AI tools and work apps change over time. To do that, it reads each service's public pricing page once a day. This page explains what the bot does, so that site operators can check it and stop it if they want to.

What it fetches

• One public pricing or documentation page per service (for a few services, the public pricing data file the vendor publishes), once per day. Nothing behind a login, no forms, no authenticated API calls.
• A single GET request, with redirects followed. If the request fails, it tries again, up to three attempts in total that day, at least 30 minutes apart.
• It reads /robots.txt first and obeys it. If robots.txt answers with a 4xx status (such as 404 Not Found), it is treated as having no restrictions. If it answers with a 5xx server error or the connection fails, the bot fetches nothing from that site.

How it identifies itself

User-Agent: TierDiffBot/1.0 (+https://tierdiff.com/bot; hello@tierdiff.com)

What it keeps

• The numbers that describe a free tier (for example "5 GB egress per month"), each with a short quote of the sentence they came from and a link to the page.
• A hash of the page, used to notice when it changes. The full page is not stored and is not republished.

How to stop it

Add a group for the bot to your robots.txt. It is picked up within 24 hours:

User-agent: TierDiffBot
Disallow: /

Or write to hello@tierdiff.com and name the site. Fetching stops the same day, and the page is marked as not tracked.

If a number is wrong

Every value on TierDiff links to the page it was read from. If you see a mistake, write to the same address with the link; the page is rechecked and the extraction rule is fixed, never by typing numbers in.