From my experience it is best to assemble a sales team and make them do some cold calling. I believe that speaking to start-ups personally will gain you more companies to post jobs on your platform.

I would also advise you to go on LinkdIn and look around the job listings there to see which companies are offering them; then contact them to perhaps post on your platform.
You should show them why you are better and why it will benefit them from posting on your platform versus others. I believe that finding the companies through LinkedIn and such will make you able to attain a large customer base rather quickly.

If you need anymore help feel free to give me a call. I am currently doing a free 15 minute consultation so just message me for the discount code.

Can you give me more details on what's required of the companies? How much are the listings? Is there anything special about your audience, etc? All of these factors influence what channel will be most effective

Hi

The best channel would be the one with the biggest difference between the customer life time value (LTV) an the cost of his acquisition (CAC); provided of course that there is not big limit on its throughput (some channels may simple have limit capacity i.e. your network).

Anyway you probably would have to try to be efficient and try to target them with some mass weapon (probably their LTV is lower than for big customers). My guess would be:
1. Some content marketing: Slideshare (both presentation on your product as well as around the efficiency of workers, recruiting etc.), Linkedin especially group discussion and sharing of your staff from your blog or slideshare. Good try would be probably also Youtube channel and youtube ads
2. Mass events. Conferences around the topic, networking events – there you can present yourself and strengthen your position as the expert on the topic
3. Cold calling – use Linkedin for it and their premium version
4. Partners and affiliation / success fees . Since they have low LTV talk with partners who are already selling them staff. In Poland we have for example a company selling cafeteria system / benefit programs. They can sell you directly or through their channels. Talk with SaaS providers for the small and medium companies (SME) especially connected w. A good partners could be companies selling e-learning solutions, training companies etc.
5. Integrate. Analyze the pains of the typical HR manager at the SME and build within your solution something which solves the pain for them i.e. does some sort of statistics their need for their bosses or helps them rank the candidates. You can also build heavy knowledge base where you keep ready-made solutions for them that make their work much easier.
6. Referral program. Create a system where people get something for referring you i.e. free training for something, access to nice software for longer etc.
That would my first choices. For more I would need more data on it

Best
Asen

Facebook is by far one of the most powerful social media channels for businesses. When asked the marketers their most important social media platform, 62% of marketers choose Facebook. With 330 million active users on Twitter, this social media platform is more commonly addressed as a “modern newsroom” of social media. "In fact, Twitter marketing is called as the “Social Currency".
LinkedIn is a great social media platform for business to business marketing. Unlike other social media channels, LinkedIn prioritizes relationship more than any other platform. In a nutshell, LinkedIn is by far one of the most important social networks that can help you in reaching out business buyers and connect with professionals. Thus, you can consider LinkedIn as one of the prime B2B social media networks.
Instagram is one of the fastest growing social media platforms with an extremely powerful social media presence globally. It has more than 800 million active users, which makes Instagram a worth social media platform for growing business.
These are the best channel by which to attract small companies to join your new platform
Besides if you do have any questions give me a call: https://clarity.fm/joy-brotonath