The firm said the move was part of its “ambitious plan to shake up the protection market.”
Advisers who want to do business with Guardian through Webline should register first using Guardian’s online self-service registration system.
Guardian is already available to financial advisers and mortgage intermediaries on iPipeline and IRESS.
Andy Peters, distribution director, Guardian, said: “We want advisers to be able to access Guardian’s protection products in a way that suits them and their business processes.
“Partnering with Synaptic is yet another important step in making sure Guardian’s products are available to as many advisers’ clients as possible.
“Synaptic has been an enthusiastic supporter of Guardian from when we first began to discuss our plans with the market.
“We’re delighted to launch with them.”
Paul Quarendon, new product development manager, Synaptic Software, said: “It’s a very exciting time to see Guardian on Webline.
“The history behind their brand, and the innovation and clarity they bring to the market at this time will strike a chord with many advisers and customers alike.
“Their focus on the customer journey is very on point, while the investment in adviser tools will ensure the provision of financial advice is relevant and timely for all customers.
“As a provider of over 10 million quote responses to our customers each month, Synaptic Software is delighted to welcome Guardian on board.”