Legal
Cookie Policy
Last updated July 25, 2026. What DC Atlas stores on your device, why, and how to change your mind at any time.
This policy explains the cookies and similar technologies used on the DC Atlas website and application, and how you control them. It sits alongside our Privacy Policy, which explains how we handle personal information more generally.
The short version: we set nothing optional unless you say yes. Until you make a choice, only strictly necessary storage is used, and no analytics or advertising technology runs at all.
1. What cookies and similar technologies are
A cookie is a small file a site stores in your browser and reads back later. Similar technologies do the same job by other means: local storage keeps values in the browser until they are cleared, and session storage keeps them until the tab is closed. This policy covers all of them, and calls them all cookies for short.
DC Atlas relies mainly on local storage rather than cookies, because the application keeps your session and your preferences in the browser rather than sending them back on every request. The rules are the same either way.
2. How we ask for your consent
The first time you visit the website you are shown a banner with two equally weighted choices: accept optional cookies, or continue with only the necessary ones. Nothing optional is set before you choose, and closing the banner without choosing leaves optional cookies off.
Your choice is stored in your browser so we do not have to ask on every page, and it is remembered for up to 12 months. You can change it whenever you like using the Cookie preferences link in the site footer, and withdrawing consent is as easy as giving it.
The application at app.dcatlas.io is signed-in software rather than a public website, so it uses only the strictly necessary storage that keeps you signed in, plus the preferences you set yourself. It runs no analytics or advertising technology.
3. What we use, by category
This is the complete list at the date of this policy. If we add anything, this table changes before it goes live.
Strictly necessary (always on)
Needed for the site and app to work: keeping you signed in, remembering your cookie choice, and protecting sign-in against automated abuse. These cannot be switched off, and they are not used to profile you.
| Name | Type | Set by | Purpose | Kept for | Where |
|---|---|---|---|---|---|
| dcatlas-consent | Local storage | DC Atlas | Stores your cookie choice so we do not ask again on every page. | Until you clear it or 12 months, whichever is sooner | Website |
| dcatlas-auth | Local storage | DC Atlas / Supabase | Holds your signed-in session so the app can authenticate your requests. | Until you sign out | App |
| dcatlas_int | Cookie | DC Atlas | Marks a browser as belonging to the DC Atlas team, so our own visits are excluded from the traffic figures we use to decide what to build. Set only when a DC Atlas staff account is signed in, holds a single fixed value that is identical on every staff device, and is removed as soon as that is no longer true. It cannot identify a visitor, and its only effect is that we record less. | 180 days, or until a non-team account signs in | Both |
| __cf_bm, cf_chl_* | Cookie | Cloudflare | Bot management and the sign-in challenge (Turnstile). Set by our hosting and anti-abuse layer when a challenge is served. | Up to 30 minutes (__cf_bm); challenge cookies are short-lived | Both |
Preferences
Remembers choices you made yourself, such as light or dark mode and how you arranged the data table. Stored in your browser and never sent to a third party.
| Name | Type | Set by | Purpose | Kept for | Where |
|---|---|---|---|---|---|
| dcatlas-theme | Local storage | DC Atlas | Remembers whether you chose light or dark mode in the app. | Until you clear it | App |
| dcatlas.explorer.grid.v2 | Local storage | DC Atlas | Remembers your column order, widths and sort in the Explorer table. | Until you clear it | App |
Analytics
Measurement of which pages are read and where visitors arrive from, so we can improve the site and know which of our work is worth doing. Most of it is first-party: our own code talking to our own servers, with no identifier attached. One part is not. Google Analytics runs in this category and sets its own cookies, so that we can tell a real visit apart from an automated one. No advertising network is involved and no advertising signal is sent to Google. If you decline, nothing in this category is loaded, stored or sent, and we do not keep a record to fill in later.
| Name | Type | Set by | Purpose | Kept for | Where |
|---|---|---|---|---|---|
| dcatlas_ft | Cookie | DC Atlas | Remembers how you first found us: the site that referred you (as a name from a fixed list, such as "google" or "linkedin", never a web address), any campaign tag on the link, and the first page you opened. Written once and not updated afterwards, so that if you create an account later we can tell which page brought you here. It holds no name, address, identifier or free text, so two people arriving from the same link on the same day have an identical cookie. | 90 days | Both |
| dcatlas_fp | Cookie | DC Atlas | Remembers the first page of your current visit, so a signup can be related to where that visit started. A page address on this site only, never a web address from elsewhere and never anything after the "?". | Until you close your browser | Both |
| _ga, _ga_* | Cookie | Google (Google Analytics 4) | Google Analytics, which we use for the one thing our own measurement cannot do: tell a real person's visit apart from an automated one. It sets a randomly generated number that lets Google recognise the same browser on a later visit. It is loaded ONLY after you accept this category. If you decline, or if your browser sends a Global Privacy Control signal, the script is never downloaded at all. Advertising storage, advertising personalisation and ad-user-data are switched off explicitly, and IP addresses are anonymised. | Up to 2 years | Website |
| Page views | Cookie | DC Atlas | No cookie is set for this: when you accept analytics, opening a page on dcatlas.io sends us the page address and your window width, with no identifier of any kind attached. It is listed here because it is the measurement this category is mostly about, and it would be misleading to describe the cookies without it. | Not stored in your browser | Website |
Advertising
Advertising and cross-site tracking technology. We do not use any, and we do not sell or share personal information for cross-context behavioural advertising.
Nothing in this category is in use at the date of this policy.
4. Third-party cookies
Cloudflare provides our hosting, content delivery and bot protection, and sets the cookies listed as strictly necessary when it serves or challenges a request. Those cookies exist to distinguish people from automated traffic and to keep the service available. They are not used for advertising or cross-site profiling.
Inside the application, map tiles are served by Mapbox, and the maps request them directly from Mapbox's network. That request carries your IP address and the tiles you are viewing, as any request to a third-party server does.
We use no advertising, retargeting or social-media tracking technology, and we do not sell or share personal information for cross-context behavioural advertising.
5. Controlling cookies yourself
- On DC Atlas: use the Cookie preferences link in the footer to change your choice at any time.
- In your browser: every major browser lets you block or delete cookies and clear site storage, usually under privacy or site settings. Blocking strictly necessary storage will sign you out and may stop parts of the application from working.
- Global Privacy Control: where your browser or extension sends a GPC signal, we treat it as an instruction to keep optional cookies off.
6. Changes to this policy
We update this policy when what we store changes, and the date at the top shows the current version. Adding a new optional cookie means asking for your consent again rather than assuming the old answer still applies.
7. Contact
Questions about this policy: contact@dcatlas.io.