# Claude session key: risks and revoking access > How a session key differs from a password and an API key, what it opens, how to check an extension, and how to close other sessions. With examples and links to the rules. Source: https://ailoot.ai/blog/en/claude-session-key-security/ Canonical: https://ailoot.ai/blog/en/claude-session-key-security/ Language: en Publisher: Ailoot (https://ailoot.ai/) Translation: guide-071 Revision: sha256-71d82e5129b14efb4328925f170986e82bbce799facaf8d4497812873066fd5f If an extension or subscription seller asks you for a string that starts with `sk-ant-sid`, don't hand it over. This string is called a session key. It isn't a password; it's already an open door to your account: with it, someone can read all your conversations and files, they won't be asked for a second factor, and you can revoke the affected session in Active sessions. If you cannot identify which session leaked, use the account-wide “Log Out” action, which logs you out too. Already handed it over? Go straight to the section on how to close access. The first two steps take a minute. Next: what this string is, what the person on the other end can see, and why Anthropic's rules consider handing it over a violation. This article does not explain how to extract the key: instead of instructions like “press F12 and copy,” it examines the consequences of giving someone access. [Practical information about working with Ailoot is in the documentation](https://ailoot.ai/docs/).
Attention This is not legal advice, and no legal recommendations are provided here. The legal section is included to show the scale of the consequences. Anthropic's rules are cited as of August 19, 2026.
## What is a Claude session key?
Key point A session key is a cookie file named `sessionKey` that claude.ai places in your browser after you sign in. Anthropic's cookie table labels its purpose “Authentication.” As long as it is there, the service assumes that you are behind the screen and asks for nothing else.
When you enter your email and the code from the message, the service verifies you once. The result of that check has to be kept somewhere, or you'd have to confirm your identity with every click. Your browser keeps it in a small file that is automatically sent to the server along with every action you take on the site. Claude uses a file called `sessionKey`. Anthropic lists it in its public cookie table: | Name | Purpose | Domains | Lifetime | |----|----|----|----| | `sessionKey` | Authentication | `.anthropic.com`, `.claude.ai`, `console.anthropic.com` | 1 month | The same table lists several other service cookies with short lifetimes, but this is the one people ask for. Anthropic describes the category this way:

Essential cookies enable the basic operation of our services and cannot be opted out of. Examples include authentication, website settings (including cookie preferences), or security.

— Anthropic, cookie table, https://privacy.claude.com/en/articles/10023541-what-cookies-does-anthropic-use
You can't opt out because without this file there is no sign-in. Its value looks like one long string that starts with `sk-ant-sid`. If someone asks you for “a string that starts with sk-ant-sid,” this is exactly what they mean. A note about the timing, so there's no confusion later. The table lists one month for the file itself, while the session lasts 28 days, and every hour that you do something on claude.ai, the clock starts over. The practical takeaway is simple: a key you hand over today works for weeks, and your own activity only pushes its expiration further out. This article uses both “session key” and “session token” to mean the same thing. ## How is a session key different from a password and an API key?
Key point Your password and verification code are checked once, when you sign in. The session key appears after that check, so it does not prompt for a second factor. API keys are managed separately from browser sessions: revoking one API key does not require signing out of the interactive account. Browser sessions can also be terminated individually through Active sessions.
These are three different things that people often blur together as “account access”: | | Password | Session key | API key | |----|----|----|----| | What it is | a request to sign in | a confirmed sign-in | a pass for a program | | When it is used | once at sign-in | with every request | with every request | | Second factor | checked along with it | already completed earlier | not involved | | What it opens | sign-in to the account | the entire account: conversations, files, settings | model calls, without conversations | | How to revoke it | change the password | terminate the affected session, or log out of all sessions if unsure | delete one key from the console | | Who is affected by revocation | depends on the sign-in system | the selected session, or every device for account-wide logout | only applications using that key | | Sharing externally | prohibited by the rules | prohibited by the rules | standard practice | The difference between the first and second columns is like the difference between a passport and an all-inclusive wristband. You show your passport at reception; they give you the wristband after checking it. Hand the wristband to someone else, and they can eat, drink, and enter your room without anyone asking for their passport. Changing a lost passport doesn't make a wristband on someone else's arm disappear. A session key works the same way. There is no need to manually replace the cookie: terminate the affected session in Active sessions. If you cannot reliably identify the leaked session, use account-wide logout to close all of them, including your own. ## Why do extensions and services ask for this key?
Key point There are four different reasons people ask for a session key, and buyers usually lump them together as “they're helping me get access.” Subscription sellers activate a plan on your account. Third-party programs route requests through your subscription to avoid paying for API access. Usage counters and conversation exports read cookies from inside the browser. The fourth category takes the key without asking at all.
Here are two real examples. There are no links to them, so we don't send them traffic. **Subscription sellers.** It looks like a service: you pay less than the official price, send over your key, and they “activate” Pro or Max on your own account. One such listing was for sale on a major digital-goods marketplace on August 19, 2026. Its terms say that only a session key is needed, and a separate line reassures readers that they won't need your password or email access. It had been sold more than a hundred times, with 38 refunds, and the seller disclaims responsibility for any potential account ban in advance, in a separate line. The Russian-language instructions for another such service end with two requests that amount to the same thing: don't log out of your Claude account until the order is complete, and stay signed in until activation is finished. Logging out kills the session and makes the key you handed over worthless. The service knows this and asks you not to do it. The instructions say nothing about what happens to the key after “activation is complete.” **Third-party programs that use Claude on the web.** claude.ai has internal endpoints that the page itself calls while you're working in it. If someone attaches another person's cookie to such a request, they can route activity through a subscription instead of paying for API access. Libraries for doing this are publicly available; the most popular have close to a thousand stars on GitHub, and their instructions have exactly one step about the key. One project keeps a whole set of other people's cookies and cycles through them, with a “blocked” status for keys in the set: its authors know in advance that some of the accounts given to them will be disabled, and have built that into the program. **Usage counters, conversation exports, integrations.** This category usually doesn't ask you to paste anything because the extension runs inside your browser and takes the cookie already stored there. The only difference from the first two categories is that the program you've granted permission to presses the copy button for you. **The fourth category steals the key.** Fake installation pages, programs that wipe everything saved in your browser, and extensions that change after an ownership transfer are covered separately below. ## What can someone with your key see?
Key point Someone with your session key sees exactly what you see when you open claude.ai. The list and contents of all conversations, files uploaded to chats and Projects, memory and custom instructions, account email, plan, and remaining usage limits. They can also write as you, and in the history it will look like you did the work.
The session key is tied to you as a whole; no particular chat is involved. So it opens the entire account: - **Conversations.** All conversations, including earlier answer versions hidden under arrows in the interface. - **Files.** Contracts, database exports, financial models, screenshots—everything you've ever dragged into a chat or put in a Project. - **Memory and custom instructions.** What you've told Claude about yourself and your work so you don't have to repeat it every time. - **Account email and plan.** You can see these on the settings page, just as you can. - **Remaining usage limits and how much more you can spend.** These are usually the numbers counters are installed to show. - **Permission to act.** They can send requests, delete conversations, and change settings. Claude's interface doesn't show full card details, so your card won't be stolen. But your subscription is inside the same account someone else has already entered, and it can be canceled with the usual button in settings.
Note What has not been checked and is therefore not claimed here. Anthropic's cookie table lists `console.anthropic.com` among the domains for `sessionKey`; this is the developer console, where API keys and their usage are shown. The domain list does not establish that the same value opens all three sites: Anthropic's help center separately notes that claude.ai and console accounts work independently, even with the same email. There has been no test on a live account, so keep this as an open question: it has not been confirmed.
Deleted conversations disappear from the history right away and from Anthropic's storage within thirty days. How long someone else can read your conversations depends on the session key's lifetime; clearing chats does not affect it at all. It's better to keep business knowledge in files in a project: you can see and edit them, and losing a session doesn't take them away. That's what a second brain is. ## Why is this more dangerous than a stolen password?
Key point A stolen password runs into the second factor, and you still have an option: change it. A session key appears after the second factor has already been completed, so it requires no further confirmation. A Claude session lasts 28 days, and every hour you work on the site, the clock starts over.
The claim “the extension bypasses two-factor protection” sounds dramatic and is also inaccurate. The extension arrives after the password has been checked, the code from the email has been entered, and the server has issued confirmation. That confirmation is what gets taken. The second property is duration. While the session is alive, the key works, and you can keep using your account as usual, extending someone else's access with every visit. The third point concerns the HttpOnly flag. It is considered the main protection for a session, and it does keep the page's own scripts from accessing the cookie. But extensions can read it through their own separate mechanism. Chromium's project description of that mechanism says:

This API also exposes the data of cookies marked HttpOnly to the extension.

— Chromium, proposal for the cookies API for extensions, https://www.chromium.org/developers/design-documents/extensions/proposed-changes/apis-under-development/proposal-chrome-extensions-cookies-api/
Current Chrome documentation confirms this indirectly: an extension receives a cookie object with an `httpOnly` property, which means it can see these cookies too. Of course, not every other extension steals cookies. It's just that “available in the store and highly rated” no longer guarantees anything, so pay attention to the permissions list. ## What do Claude's rules say about this?
Key point Section 2 of Anthropic's Consumer Terms prohibits sharing account credentials, and section 3 prohibits accessing the service by automated means without an API key. You are responsible for everything that happens under your account. Section 13 allows Anthropic to suspend or terminate access at any time and without notice, and handing over one session key touches all three provisions at once.
Section 2 of [Anthropic's Consumer Terms](https://www.anthropic.com/legal/consumer-terms), verbatim:

You may not share your account credentials, your Anthropic API key, or account credentials with anyone, or provide anyone else with access to your account.

— Anthropic, Consumer Terms, section 2, https://www.anthropic.com/legal/consumer-terms
Handing over a session key falls squarely under this provision. The same section states that the account owner is responsible for all activity under the account and must immediately notify support of any unauthorized access. Section 3 separately prohibits accessing the service “by automated or non-human means, whether through a bot, script or otherwise” if it is not through an API key. Section 13 gives Anthropic the right to suspend or terminate access at any time without notice if the company considers the terms to have been materially violated. Handing over one key touches all three provisions at once. The Claude Code documentation says this about third-party programs:

Anthropic does not permit third-party developers to offer Claude.ai sign-in or route requests through Free, Pro, and Max plan credentials on behalf of their users. Anthropic reserves the right to take action to enforce these restrictions and may do so without prior notice.

— Anthropic, Claude Code documentation, authentication section, https://code.claude.com/docs/en/legal-and-compliance
A qualification about what is being claimed: no public statement from Anthropic saying “we ban people for sharing sessionKey” was found, so the article does not attribute that wording to the company. The documents show that the rules explicitly prohibit it, the account owner is responsible, and access may be disabled without notice. There are indirect signs as well: third-party programs include “blocked” as an ordinary key status. There is a second prohibition too. The usage rules prohibit bypassing a block through another account and providing access to someone who has already been disabled. If someone bought your key for that purpose, the violation will be recorded against your account. Other reasons Anthropic closes access are collected in the article on [why Claude accounts are banned](https://ailoot.ai/blog/en/claude-account-suspension-appeal/). ## How do you check an extension before and after installing it?
Key point You can see only a little before installation: the section about data in the store listing and whether the extension can be found through store search at all. Everything else is checked on extensions already installed, and takes about ten minutes. The main warning sign is an extension unrelated to Claude having permission to work on claude.ai itself.
**What you can see before installation.** The store listing has a privacy section that says what data the extension collects and shares. The second clue is how you found it. If the extension can't be found through store search and can only be installed from a direct link in someone else's message, treat that as a warning sign. **What to check among extensions already installed.** Go through these five steps today, across the whole list. 1. ### Open the extensions list and check permissions The address is `chrome://extensions`; for the extension you want, click “Details.” In Edge, the address is `edge://extensions`. Arc and other browsers based on the same engine use the same `chrome://extensions` address. 2. ### Look for a line about claude.ai Chrome doesn't show a separate warning about cookie access, so look at the list of sites instead. A line such as “Read and change your data on claude.ai” means the extension works inside your Claude session. That's normal for a usage counter. It's not normal when this line appears for an extension unrelated to Claude. 3. ### Check whether access to all sites is allowed The “Site access” section may show “On all sites.” That lets the extension access your bank, email, and your site's admin panel too. A Claude usage counter has no need for that under any circumstances. 4. ### Reduce access to the minimum In the same place, change “On all sites” to “On specific sites” or “On click.” The extension will keep working where it needs to and stop reading everything else. 5. ### Check whether ownership has changed Extensions are resold, and a new owner may release an update that installs silently. Signs include a changed publisher or support address, an update after a long quiet period with no clear description of changes, new permissions that weren't in the previous version, or a sudden flood of reviews reporting replaced search results and ads. There's also a sixth check for anyone who wants to dig deeper: turn on “Developer mode” on the same page, click the blue link under the extension, then use the “Network” tab to see where requests go. They should go only to claude.ai itself and the extension author's site. If a third address appears that isn't mentioned in the description, the extension is sending your data somewhere else. This check is tedious; the first five steps are enough without it. And ask yourself one last question: why does this task need the key to your whole account? You can show remaining usage limits without it, and export conversations too. ## What should you do if you've already handed over the key?
Key point There are six steps, and do the first two in the next five minutes. First remove the extension, or the next key will leak the same way. Then check the active sessions list and log out of all of them. Changing your password by itself does not kill someone else's session, so that comes third.
1. ### Remove the extension or revoke its access While it's installed, any new key will go the same way. Go to `chrome://extensions` and click “Remove.” 2. ### See who is currently in your account On claude.ai, open “Settings,” the “Account” section, and the “Active sessions” block. For each session, you can see the device and browser, approximate location based on the connection address, and the time it was last used; your current session is marked with a “Current session” icon. An unfamiliar city or someone else's browser in the list leaves nothing to guess about. You can close an individual session using the three-dot menu, “Terminate,” and then confirmation. 3. ### Log out of all sessions at once In the same place, “Settings” → “Account,” there is a “Log Out” button. It logs you out on all devices: in browsers, mobile apps, and desktop programs. This closes all active sessions. Terminating the affected session individually also revokes that session; use account-wide logout when you cannot reliably identify it. Anthropic notes that the Claude mobile apps for iOS and Android don't have this button; log out from a browser. 4. ### Change your password if you sign in with one Skip this step if you sign in with “Continue with Google” or through a work account. The order matters: changing your password prevents future sign-ins, but doesn't break sessions that are already open, so do this after step 3. 5. ### Notify Anthropic The Consumer Terms require you to immediately report unauthorized access by emailing . Don't send the email just to check a box: if someone has already done something under your account, it records that you reported it yourself. 6. ### Review your keys and your history If you have a developer console account, check the “API Keys” section and delete anything you're unsure about. Anthropic recommends revoking a key as soon as you suspect a leak and setting usage limits at the same time. Then clear sensitive conversations and files in Projects: they disappear from history immediately and from storage within thirty days. To download a complete copy of your conversations for review, go to “Settings” → “Privacy” → “Export data”; the archive link is available for one day. Also check whether anything leaked earlier by another route: see the article on [Claude chats appearing in Google search](https://ailoot.ai/blog/en/claude-shared-chats-search-privacy/) for public conversation links. One separate question makes people hesitate over step three: what happens to a subscription they've already paid a seller for? The “Log Out” button closes sessions and doesn't touch the subscription: the plan is tied to the account and can be canceled separately with a button in the “Billing” section. So you can log out of all sessions and keep the paid plan. The seller's own terms, however, disclaim responsibility for bans, so you have no protection here; the decision “I'll wait because I don't want to lose the money” protects you from exactly nothing. There's one thing you can't undo: what's been read has been read. And if chats contained customer data, talk to the person responsible for personal data at your organization. ## How can you do the same thing without a key?
Key point Each of the four reasons someone asks for the key can be handled through the normal method, without handing over a session key. Usage is visible in the account itself, conversations can be exported with a button, your service can be connected using an API key, and external services such as Notion can be connected using official connectors. There is no safe way at all to get someone else's subscription.
| Task | Standard way to handle it | |----|----| | See remaining usage limits | Usage page in the account itself, the `/usage` command in Claude Code, third-party counters that don't access the key | | Export conversations | “Settings” → “Privacy” → “Export data”; the archive arrives by email | | Connect Claude to your service or bot | API key in the developer console, with a separate key for each environment | | Connect Claude to Notion, a drive, or a calendar | Official connectors: the service itself grants and revokes access | | Work with Claude directly in the browser | Official Claude in Chrome extension | | Get someone else's subscription for less | There is no standard way | You can revoke API keys one at a time without closing your browser sessions. Browser sessions also support individual termination, but the controls and scope are separate: remove a compromised API key in the console, or terminate an affected web session in Active sessions. Anthropic recommends using different keys for different environments—development, testing, and production—and changing them on a schedule, for example every 90 days. See the [subscription renewal instructions](https://ailoot.ai/blog/en/claude-subscription-renewal-cancellation/). A separate note about the official extension, because it can access conversations too. The difference is that it uses your Claude sign-in on your own machine and doesn't send anything outside: the key doesn't go anywhere. Even so, Anthropic is cautious in its guidance: it recommends running the extension in a separate browser profile without access to banking, medical, or government accounts. If the platform's creator is that careful with its own product, be even more careful with a third-party extension that can access claude.ai. ## What else do people ask about session keys?
Key point Six questions people ask most often. Changing your password doesn't close someone else's session: the session was authenticated earlier and continues on its own. A key lasts 28 days, but those days are counted from your last activity on the site, so every visit moves someone else's access further into the future. A verified publisher badge in an extension store doesn't guarantee anything either.
### Frequently asked questions I changed my password. Is the other person's access closed? No. Changing your password prevents future sign-ins, but the session key that was issued keeps working because the session was authenticated earlier. Terminate the affected session in “Settings” → “Account” → “Active sessions,” or use the account-wide “Log Out” action if you cannot identify which session leaked. A month has passed, so the key no longer works, right? Not necessarily. Anthropic says a web session lasts 28 days and is extended by up to 28 days every hour while you're doing something on claude.ai. As long as you use your account, the expiration moves forward, and someone else's access moves forward with it. The service promises to delete the key after activation. Can I trust that? It's impossible to check this, either before or after. You can revoke the affected session yourself. If you cannot identify it reliably, log out of all sessions rather than trusting a promise to delete the copied value. Sellers, incidentally, explicitly ask you not to do this before activation is complete. The extension is in the official store and has a verified publisher badge. Isn't that a guarantee? The badge was granted to an earlier version; it guarantees nothing about the one currently installed on your device. There's nothing secret in my Claude account. Is there still a risk? Look at the account from another angle: it contains not only what you consider secret, but also your email, plan, memory containing information about your work, and everything you've ever uploaded to chats. It also allows actions in your name, and Anthropic's rules allow the account to be disabled without notice. How can I tell whether someone has already used the key? Open “Settings” → “Account” → “Active sessions.” The list shows each session's device, browser, approximate location, and last-used time. An unfamiliar entry means someone is in the account.
## What to do next
Key point If you haven't handed over your session key, don't: the task people ask for it to accomplish can almost always be handled normally, without access to your whole account. If you have handed it over, open “Settings” → “Account” → “Log Out.” It takes a minute, and the other person's session stops working immediately. In either case, finish by reviewing your installed extensions: it takes about ten minutes and is usually an unpleasant surprise.
Reviewing your extensions takes about ten minutes and is usually an unpleasant surprise. Open `chrome://extensions` and count how many have “On all sites” access. Change anything that can work without it to “On click.” For the rest, check whether claude.ai is listed for an extension unrelated to Claude. And here's a rule that applies beyond this situation. If a tool asks for access to your entire account even though it could use a separate key, it's saving itself work at your expense. The article [Is it safe to give Claude Code access to your data?](https://ailoot.ai/blog/en/claude-code-data-access-safety/) explains what is and isn't worth giving to AI tools. See [vibe-coding security](https://ailoot.ai/blog/en/vibe-coding-security/) for vulnerabilities in things built with vibe coding.
### Sources - [Anthropic - What cookies does Anthropic use? Full table](https://privacy.claude.com/en/articles/10023541-what-cookies-does-anthropic-use) - [Anthropic - Consumer Terms](https://www.anthropic.com/legal/consumer-terms) - [Anthropic - Usage Policy](https://www.anthropic.com/legal/aup) - [Claude Code - Legal issues and authentication](https://code.claude.com/docs/en/legal-and-compliance) - [Anthropic - How to log out of all active sessions and how long a session lasts](https://support.claude.com/en/articles/10310342-how-do-i-log-out-of-all-active-sessions) - [Anthropic - Managing active sessions](https://support.claude.com/en/articles/13124001-managing-your-active-sessions) - [Anthropic - How to use Claude in Chrome safely](https://support.claude.com/en/articles/12902428-use-claude-in-chrome-safely) - [Anthropic - API key best practices](https://support.claude.com/en/articles/9767949-api-key-best-practices-keeping-your-keys-safe-and-secure) - [Anthropic - Exporting your data](https://support.claude.com/en/articles/9450526-export-your-claude-data) - [Anthropic - How long do you store my data?](https://privacy.claude.com/en/articles/10023548-how-long-do-you-store-my-data) - [Anthropic - Canceling a subscription in Billing](https://support.claude.com/en/articles/8325617-how-do-i-cancel-my-paid-claude-subscription) - [Anthropic - Claude and console accounts work independently](https://support.claude.com/en/articles/8987223-does-my-claude-ai-account-work-for-the-developer-console) - [Claude Code - The /usage command and managing costs](https://code.claude.com/docs/en/costs) - [Chrome - The chrome.cookies API and permission requirements](https://developer.chrome.com/docs/extensions/reference/api/cookies) - [Chrome - How to declare extension permissions](https://developer.chrome.com/docs/extensions/develop/concepts/declare-permissions) - [Chrome - Debugging extensions](https://developer.chrome.com/docs/extensions/get-started/tutorial/debug) - [Chromium - Proposal for the cookies API and access to HttpOnly cookies](https://www.chromium.org/developers/design-documents/extensions/proposed-changes/apis-under-development/proposal-chrome-extensions-cookies-api/)
[Open Ailoot](https://ailoot.ai/). ## Questions about Claude session key: risks and revoking access ### Do I have to log out of every device to revoke a leaked session? If you can identify the affected session, terminate it in Settings → Account → Active sessions. If you cannot identify which session leaked, use account-wide Log Out; that also ends your own sessions. ### What should I do before signing in again after an extension leaked a key? Remove the extension or revoke its access first so it cannot capture the next session. Then revoke the affected session or all sessions as appropriate, and review account history and any separately managed API keys. ## Ailoot · The company and its project portfolio Ailoot combines established operating experience, a large client base, stable service and ongoing KPI control. The company and its project portfolio: millions of customers; monthly sales in the billions. Ailoot brings that operating experience to API access for AI features in customer products, agents, applications and automations.