---
id: index
slug: /
title: Introduction
---

ORY Kratos is an API-first Identity and User Management system that is built
according to
[cloud architecture best practices](https://www.ory.sh/docs/ecosystem/software-architecture-philosophy/).
It implements core use cases that almost every software application needs to
deal with:

- **Self-service Login and Registration**: Allow end-users to create and sign
  into accounts (we call them **identities**) using Username / Email and
  password combinations, Social Sign In ("Sign in with Google, GitHub"),
  Passwordless flows, and others.
- **Multi-Factor Authentication (MFA/2FA)**: Support protocols such as TOTP
  ([RFC 6238](https://tools.ietf.org/html/rfc6238) and
  [IETF RFC 4226](https://tools.ietf.org/html/rfc4226) - better known as
  [Google Authenticator](https://en.wikipedia.org/wiki/Google_Authenticator))
- **Account Verification**: Verify that an E-Mail address, phone number, or
  physical address actually belong to that identity.
- **Account Recovery**: Recover access using "Forgot Password" flows, Security
  Codes (in case of MFA device loss), etc.
- **Profile and Account Management**: Update passwords, personal details, email
  addresses, linked social profiles using secure flows.
- **Admin APIs**: Import, update, delete identities.

Identity is a hard problem and ORY Kratos solves it in a unique way. We value
security, flexibility, and integration with cloud technology (such as
Kubernetes) most:

- ORY Kratos does not ship an HTML Rendering Engine. You can build your own UI
  (or use our example UIs) in the language and framework you feel most
  comfortable with.
- The workflow engine allows you to fully customize your user experience.
  Whether your users need to activate their account after registration, or have
  a multi-step (progressive) registration - it's all possible!
- One Identity Data Model does not fit all - you may have customers that need a
  billing address, internal support staff that is assigned to a cost center, and
  that smart fridge on floor 4. You can express the different data models using
  [JSON Schema](https://json-schema.org/) and make the system work for you - not
  the other way around.

To learn more about what's different and how ORY Kratos compares to other open
source solutions, head over to [Concepts](./concepts/index.md) and
[Comparison](./further-reading/comparison.md).

ORY Kratos isn't just about features; it stands out because it runs on any
operating system (Linux, macOS, Windows) and on most processors (i386, amd64,
arm, etc.). The compiled binary has _no system or library or file dependencies_
and can be run as a single, static binary on top of, for example, a raw Linux
kernel. The binary and Docker image are each less than 20MB in size.

ORY Kratos scales horizontally without effort. The only external dependency is
an RDBMS - we currently support SQLite, PostgreSQL, MySQL, CockroachDB. You will
not need memcached, etcd, or any other system to scale ORY Kratos.

We believe in strong separation of concerns, which is a guiding principle in the
design of each ORY project. As such, we build software that solves specific
problems very well and offloads adjacent issues (such as a user interface) to
other applications.
