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Technologies / Fastmail / OpenAI

Companies using Fastmail and OpenAI

3 companies in our data have public evidence for both Fastmail and OpenAI, and 3 name both in their own subprocessor list. Each company below links to the source for every claim. Our coverage is partial, so this is not everyone.

3companies use both
20%of Fastmail users
under 1%of OpenAI users
3name both as subprocessors

The companies

Strongest evidence first: a company naming both in its own subprocessor list comes before one seen on its website or in job postings.

Subprocessor listPrivacy policyWebsiteJob postings

CompanyFastmailOpenAI
draw.io
Sendmarcsendmarc.comSendmarc provides a platform for managing DMARC, SPF, and DKIM email authentication across domains.Cybersecurity
SimpleLocalizesimplelocalize.ioSimpleLocalize provides a web-based translation editor and platform for managing translations and automating localization workflows for software projects.Developer tools

The two technologies

Fastmail

Email and communications

Fastmail is a paid email hosting service offering email, calendar, and contacts, with options for private email addresses and offline access. It is used by individuals and businesses to send, receive, organize, and manage email, calendars, and contacts across devices.

Summarized from fastmail.com on 8 Nov 2026.

20% of the 15 companies we see using Fastmail also show the other.

All 15 companies using Fastmail12 name it as a subprocessorMore in Email and communications

OpenAI

AI and LLM providers

OpenAI is a platform that provides an API for building with OpenAI models. It is used to access models, tools, and services for tasks such as text generation, image generation, audio, and agents.

Summarized from developers.openai.com on 8 Nov 2026.

under 1% of the 3,285 companies we see using OpenAI also show the other.

All 3,285 companies using OpenAI2,522 name it as a subprocessorMore in AI and LLM providers

Other pairs

Companies with their own evidence for both.

More with Fastmail

Cloudflare15companiesStripe9companiesAmazon Web Services6companiesAnthropic6companiesHetzner6companiesGoogle5companies

More with OpenAI

Cloudflare3,278companiesGoogle Workspace2,473companiesAnthropic1,993companiesAmazon Web Services1,891companiesStripe1,643companiesGoogle1,547companies

Questions

How many companies use both Fastmail and OpenAI?

3 companies in StrataDB's data have public evidence for both, and 3 of them name both in their own subprocessor list, the strongest evidence we hold. Our coverage is partial, so the real number is higher.

Which companies use Fastmail and OpenAI?

draw.io, Sendmarc and SimpleLocalize. Each one links to the evidence behind it.

How does StrataDB know a company uses Fastmail and OpenAI?

From four kinds of public evidence: subprocessor lists, privacy policies, website code and job postings. Each is kept apart with its source and the date we saw it. A company missing here means we found no evidence, not that it does not use them.

Find every company using Fastmail and OpenAI

See the full list with the source for each company, and run the same lookup for any technology from the API, Claude or your browser.

  • Every company and vendor, with its public source
  • 100 API calls a month, plus MCP and the Chrome extension
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