# 5. Creating the APIs

As a Solver integrating with SYMMIO, you’ll need to include **REST APIs**, to allow frontends to display data like available symbols, retrieving open interest and notional caps.

## REST APIs

Detailed documentation about REST API endpoint queries and returned data can be found in the following section. It's recommended that solvers follow the same structure in their endpoints to integrate with frontends easily.

The full list of endpoints that solvers can integrate is here, however not all are essential for an implementation. Essential endpoints are listed below:

### [**GET Contract Symbols: /contract-symbols**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-contract-symbols)

### [
**GET Open Interest: /open-interest**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-open-interest)

### [
**GET Notional Cap by Symbol: /notional\_cap/{symbol\_id}**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-notional-cap)

### [
**GET Price Range by Symbol: /price-range/{symbol}**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-price-range)

### [
**GET Locked Parameters for a Symbol: /get\_locked\_params/{symbol}?leverage={leverage}**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-get-locked-params)

### [
**GET Funding Information: /get\_funding\_info**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-get-funding-info)

### [**GET Error Codes: /error\_codes**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/get-error-codes)

### [**POST Position Information: /position\_state/\<offset>/\<size>**](https://docs.symm.io/liquidity-provider-documentation/building-a-solver-on-symmio/5.-creating-the-apis/post-position-state)