Universal OLT Management API

I run a network that mixes Huawei, ZTE and BDCOM OLTs (including BDCOM E-PON and G-PON units), and I need a single back-end service that talks to all of them. The goal is a lightweight, well-documented... (Budget: £20 - £250 GBP, Jobs: API Development, cURL, Documentation, Git, JSON, Network Administration, Network Engineering, RESTful)