2fa.cn valid
2FA.CN
2FA.CN is a free online two-factor authentication tool for generating Time-based One-Time Password (TOTP) verification codes directly in a web browser.
For agents: Free browser-based TOTP two-factor authentication tool for generating one-time verification codes. Very thin llms.txt material.
two-factor authenticationtotpone-time passwordbrowser toolfree tool
- Authority
- 49 reach 9 · trust 5 · quality 20 · freshness 15
- Tier
- listed
- llms.txt
- https://2fa.cn/llms.txt
- llms-full.txt
- https://2fa.cn/llms-full.txt
- Sections
- 8
- Links
- 0
- Size
- 2507 bytes
- Popularity rank
- #185136
- Country
- China
- Categories
- Cybersecurity · Authentication and identity
- For agents
- Documentation: developer or product docs worth reading, nothing to call
- Audience
- consumers · agents can: read docs · zh
- First seen
- 2026-10-18T15:08:56.294Z
- Last checked
- 2026-10-18T21:37:02.035Z
- Badge
Their llms.txt
The beginning of the file, from our validated copy saved 2026-10-22T10:12:48.187Z. Cached copy · Source on 2fa.cn
# 2FA.CN
> 2FA.CN is a free online two-factor authentication tool for generating Time-based One-Time Password (TOTP) verification codes directly in a web browser.
## About
2FA.CN provides an online authenticator for users who need to generate temporary verification codes for accounts and services that support TOTP-based two-factor authentication.
The service is designed to be simple, fast, and accessible without requiring users to install a dedicated authenticator application.
2FA.CN supports standard TOTP authentication workflows and can be used with services that provide a compatible TOTP secret key or QR code.
## Main Features
- Online TOTP code generation
- Two-factor authentication code generation
- OTP verification code generation
- QR code based TOTP setup
- Manual secret key input
- Multiple TOTP account support
- Browser-based authentication
- Mobile and desktop support
- RFC 6238 compatible TOTP generation
- Local browser-based processing
## Common Use Cases
Users can use 2FA.CN for TOTP-enabled accounts and services, including:
- Google accounts
- Microsoft accounts
- GitHub
- GitLab
- Amazon Web Services
- Discord
- Facebook
- Instagram
- X
- Dropbox
- Steam
- PayPal
- Cryptocurrency platforms
- Other services supporting standard TOTP authentication
## Security
2FA.CN is designed to process TOTP information in the user's browser.
Users should only enter authentication secrets into services they trust and should never share their secret keys with other people.
Two-factor authentication secrets are sensitive security credentials and should be protected accordingly.
## TOTP Standard
2FA.CN is based on the Time-based One-Time Password algorithm described by RFC 6238.
TOTP generates a temporary verification code from a shared secret and the current time.
The generated code changes periodically according to the configured time interval.
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Machine-readable: GET /v1/resolve?q=2fa.cn · GET /v1/domain/2fa.cn · this page as Accept: application/json or text/markdown · MCP lookup_domain
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