Privacy Policy

Last updated: June 30, 2026

This Privacy Policy explains how Stella Growth Intelligence ("Stella," "we," "us," or "our") collects, uses, shares, and protects information in connection with our causal marketing-measurement platform and related websites and services (the "Service"). Stella provides incrementality testing, geo holdout experiments, media mix modeling, and multi-touch attribution for businesses that advertise online.

By using the Service or connecting a third-party platform to Stella, you agree to this Policy. If you do not agree, do not use the Service.

1. Who we are and how to contact us

Stella Growth Intelligence is the data controller for personal information we process about our account holders, and a data processor (or service provider) for the data we process on behalf of our customers (see Section 11). You can reach us at:

2. Information we collect

Account and billing information

When you create an account we collect your name, work email, organization name, and a hashed password. Payments are processed by our payment provider; we do not store full card numbers.

Data from connected advertising platforms

When you connect an advertising platform (such as Meta, Google, Pinterest, Snapchat, or TikTok), you authorize Stella to access data through that platform's API to provide the Service. For causal measurement we primarily ingest aggregated, geographic-level data, for example campaign and ad performance, spend, impressions, clicks, and conversions reported at the DMA (designated market area), state, or region level, together with campaign and channel metadata. This data is used to model incrementality, not to build profiles of individual people.

Data from connected sales and e-commerce platforms

When you connect a sales or e-commerce platform (such as Shopify or Amazon), we ingest order and revenue data, typically aggregated to the same geographic and time levels, so we can match marketing activity to outcomes and run holdout experiments.

Website and app analytics data (multi-touch attribution)

If you deploy Stella's tracking pixel on your website or app, we collect interaction data about your visitors so we can attribute conversions across touchpoints. This may include: pages viewed, referrers, UTM parameters, advertising click identifiers (for example gclid, fbclid, ttclid, and similar), device and browser information, IP address, timestamps, and cookie or local-storage identifiers. When a visitor converts, we associate the touchpoints with the conversion and may collect order details and a hashed (irreversible) version of the customer's email address so the conversion can be matched. We use this to stitch together the customer journey across channels.

Data you upload

You may upload data directly (for example CSV files or Google Sheets) for analysis.

Usage and log data

We collect standard logs (IP address, browser, actions taken) to operate and secure the Service.

3. How we use information

  • To provide the Service: ingesting and matching advertising and sales data, running holdout experiments and causal/incrementality analysis, building media mix models, and performing multi-touch attribution.
  • To return measurement results, dashboards, and recommendations to you.
  • To send conversion and incremental-purchase events back to your connected advertising platforms at your direction (see Section 4).
  • To provide support, secure the Service, prevent fraud and abuse, and process billing.
  • To improve the Service using aggregated and de-identified data.
  • To comply with legal obligations.

4. How our closed-loop measurement works

Stella runs a closed-loop measurement system. We pull geographic-level data from your connected advertising and sales platforms, match it together, and run holdout experiments and models to estimate the incremental impact of your marketing. For multi-touch attribution, we record touchpoints (such as UTM parameters and ad click identifiers) and stitch them into customer journeys.

Where you enable it, Stella also sends conversion and incremental-purchase events back to the advertising platforms you have connected, through those platforms' conversion APIs, so the platforms can match conversions and optimize your campaigns. These outbound events relate only to your own campaigns and may include hashed identifiers (such as a hashed email address), advertising click identifiers, UTM parameters, and the event value. We transmit this on your behalf and at your direction, only to the platforms you have connected. We do not send your data to advertising platforms for any other advertiser's benefit.

5. How we share information

We do not sell or rent personal information, and we do not share it for cross-context behavioral advertising. We share information only as follows:

  • Service providers (subprocessors): cloud hosting and data-warehouse providers, data-ingestion providers, payment processors, email providers, and security and analytics vendors, all under contractual confidentiality and data-protection obligations, and only as needed to run the Service.
  • Platforms you connect: to provide the Service to you (for example, sending conversion events back to an advertising platform you connected).
  • Legal and safety: where required by law, to enforce our terms, or to protect rights, safety, and security.
  • Business transfers: in connection with a merger, acquisition, or sale of assets, subject to this Policy.

6. Advertising and e-commerce platform data

When you connect a platform, you authorize Stella to access data through that platform's API solely to provide the Service to you. For every connected platform: we access only the data needed for measurement; we do not sell, rent, or redistribute platform data or platform-derived data to third parties; and when you disconnect the platform or close your account, we delete the data derived from that platform from our active systems within 30 days, except where we must retain it to comply with law (see Section 8). Stella is an independent service and is not endorsed by, affiliated with, sponsored by, or otherwise associated withany of the platforms below. Each platform's own privacy policy and terms govern your relationship with that platform.

Pinterest

Stella uses the Pinterest API. Our access and use of Pinterest data is also subject to the Pinterest Privacy Policy and the Pinterest Terms of Service. Stella's website and application are not endorsed by or affiliated with Pinterest. We use Pinterest API data only to provide measurement to you, and we do not resell or redistribute Pinterest content or Pinterest-derived data to any third party. If you disconnect your Pinterest account or close your Stella account, we delete Pinterest-derived data from our active systems within 30 days, subject to legal retention requirements.

Meta (Facebook and Instagram)

Stella uses Meta's marketing and conversions APIs. We ingest aggregated, geographic-level ad performance and, where you enable it, send conversion events (including hashed identifiers) back to Meta for your campaigns. Stella is not affiliated with or endorsed by Meta. We do not resell or redistribute Meta data or Meta-derived data, and we delete it on disconnection as described above.

Google

Stella uses Google APIs (including the Google Ads API). Our use of information received from Google APIs adheres to the Google API Services User Data Policy, including its Limited Use requirements. Stella is not affiliated with or endorsed by Google. We do not resell or redistribute Google data or Google-derived data, and we delete it on disconnection as described above.

TikTok

Stella uses TikTok's marketing and events APIs. We ingest aggregated ad performance and, where enabled, send conversion events (including hashed identifiers) back to TikTok for your campaigns. Stella is not affiliated with or endorsed by TikTok. We do not resell or redistribute TikTok data or TikTok-derived data, and we delete it on disconnection as described above.

Snapchat

Stella uses Snap's marketing and conversions APIs. We ingest aggregated ad performance and, where enabled, send conversion events (including hashed identifiers) back to Snap for your campaigns. Stella is not affiliated with or endorsed by Snap Inc. We do not resell or redistribute Snap data or Snap-derived data, and we delete it on disconnection as described above.

Shopify and other e-commerce platforms

Stella uses the APIs of connected e-commerce platforms (such as Shopify and Amazon) to ingest order and revenue data used for measurement. Stella is not affiliated with or endorsed by these platforms. We do not resell or redistribute this data or data derived from it, and we delete it on disconnection as described above.

7. Identifiers, hashing, and cookies

Personal identifiers such as email addresses that are sent to advertising platforms for conversion matching are hashed (for example with SHA-256) before transmission. We do not provide raw email addresses or phone numbers to advertising platforms beyond what their conversion APIs require in hashed form. Advertising click identifiers and UTM parameters are pseudonymous and are used to attribute touchpoints.

Stella's tracking pixel uses first-party cookies and similar technologies to recognize touchpoints and attribute conversions. Where the pixel is deployed on a customer's website, the customer is responsible for obtaining any required consent and for honoring applicable consent signals; Stella honors documented consent and opt-out signals it receives. Visitors can generally manage cookies through their browser settings.

8. Data retention

We retain account information for as long as your account is active. After your account is closed, we retain personal data for up to 90 days for recovery purposes and then delete or de-identify it, unless a longer period is required by law. Data derived from a connected platform is deleted from active systems within 30 days of disconnection. We may retain aggregated or de-identified data that does not identify any individual.

9. Data security

We use technical and organizational measures designed to protect information, including encryption in transit and at rest, access controls, and least-privilege practices. No method of transmission or storage is completely secure, and we cannot guarantee absolute security.

10. Your privacy rights

Depending on where you live, you may have rights to access, correct, delete, port, or restrict processing of your personal information, and to object to certain processing. We comply with applicable laws including the EU and UK GDPR, the California Consumer Privacy Act as amended by the CPRA, PIPEDA (Canada), and the LGPD (Brazil). To exercise a right, email marketing-admin@stellaheystella.com. We do not sell personal information or share it for cross-context behavioral advertising, and we do not discriminate against you for exercising your rights.

11. Data we process on behalf of customers

For data processed through the Service about our customers' own advertising accounts and website visitors, our customer is the controller and Stella acts as a processor or service provider acting on the customer's instructions. Our customers are responsible for having a lawful basis for the processing, for providing their own privacy notices to their end users, and for obtaining any consent required (including for the tracking pixel and for sending hashed identifiers to advertising platforms). If you are an end user and wish to exercise your rights, please contact the business whose website you visited; we will support that business in responding.

12. International data transfers

We are based in the United States and may process information in the United States and other countries. Where required, we use appropriate safeguards (such as standard contractual clauses) for international transfers.

13. Children's privacy

The Service is for businesses and is not directed to children. We do not knowingly collect personal information from children under 16.

14. Changes to this Policy

We may update this Policy from time to time. We will post the updated version with a new "Last updated" date and, where appropriate, provide additional notice.

15. Contact us

Questions about this Policy or our data practices? Email marketing-admin@stellaheystella.com or write to us at the address in Section 1.