# Rell Stdlib · Rell standard library · Chromia Docs (concept)

> The Rell Standard Library contains the essential building blocks for writing your rell dapp. It contains: Basic data types Cryptographic functions Chain me

Source: https://docs.chromia.com/pages/rell-stdlib/

API REFERENCE

# Rell Stdlib

The Rell Standard Library contains the essential building blocks for writing your rell dapp. It contains:

* Basic data types
* Cryptographic functions
* Chain metadata
* Test library functions

## Namespaces

[[root]](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/root/)
:   Global namespace containing types and functions accessible without any namespace prefix.

[rell.time](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell.time/)
:   Date/time formatting and parsing utilities. Convert between millisecond timestamps and human-readable text via configurable rell.time.format patterns.

[rell](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell/)
:   Meta information about rell types.

[crypto](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/crypto/)
:   Cryptographic functions.

[chain\_context](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/chain_context/)
:   Blockchain metadata and module arguments.

[op\_context](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/op_context/)
:   Functions and properties that are only accessible withing the scope of an operation.

[rell.test.keypairs](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell.test.keypairs/)
:   Predefined keypairs that can be used for testing.

[rell.test.privkeys](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell.test.privkeys/)
:   Predefined private keys that can be used for testing.

[rell.test.pubkeys](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell.test.pubkeys/)
:   Predefined public keys that can be used for testing.

[rell.test](https://docs.chromia.com/pages/rell-stdlib/-rell-system-library/rell.test/)
:   The rell.test namespace is only accessible within test modules

[View this page on docs.chromia.com](https://docs.chromia.com/pages/rell-stdlib/index.html)Generated API reference, mirrored from the live docs