8 Essential Growth-Hacking Tools to Build Your Business Step 1: Research what other companies have done successfully to grow. Step 2: Copy them.

One of the biggest challenges startups face is scaling user and customer bases. This is particularly daunting for startups and smaller companies: They're marketing without a well-known brand or the financial resources needed to make a substantial impact through conventional marketing outlets like radio, TV or paid digital advertising.

So, what's a startup to do?

This is where growth-hacking comes in. Growth-hacking was the key, for example, to jump-starting growth for Airbnb, which essentially "hacked" Craigslist to acquire new users and get more people to post apartment rentals on its site.

Growth-hacking is about using your creativity to find cost-effective, scalable ways to acquire and retain as many users as possible. I myself was initially intimidated by the concept when I first heard of it, but at the end of the day, it's really just a process of experimentation: coming up with an idea, testing it, tracking it and analyzing the results, then working to make it more effective.

Related: The Definitive Guide for Growth Hacking (Infographic)

Throughout the years, at iSeeCars, we've experimented with many ideas and used many tools. Here are a few of the tools that have been essential in helping us grow our business and brand.

1. Quora -- research-tested growth-hacking ideas

For inspiration, research what other companies have done successfully. If you're curious about how a certain company got so big so quickly, a good place to gain some insight is on Quora, where founders and early employees offer a perspective on their company's growth and success. Here are examples of growth-hacking techniques some iconic companies used back when they were startups. They might be worth trying.

Most of these examples focused on acquiring users. But, equally important is retaining users. When Twitter was still young, for example, it had a hard time getting new users to come back again. So, it dug into customer-usage data and found that users who didn't follow at least five to 10 users on the first day they signed up were much less likely to become long-term users.

With this epiphany, Twitter revamped its product to create an experience that made it much easier and quicker for users to get to the five to 10 followers from day one. After the change, the content that users saw were the tweets that followers posted. If users chose the followers that interested them, there was a good chance the content they saw would be interesting and more relevant to them.

You could do something similar: Dig into your data and better understand how people use your website or app to get ideas on making your product stickier.

Cost: Free

2. Google Analytics -- analyze data to identify opportunities

Google Analytics may be something you already use. We use it extensively to analyze the traffic and usage on both our desktop and mobile sites. We measure everything a user can do on our site; anything a user clicks on is tracked.

The data gives us a good picture of how users engage with our product and how many drop off before they complete an "event" -- like filling out a form or signing up for an email alert. If your site drives a lot of password-protected users, use Kissmetrics (around $200 per month). That platform shows data from the perspective of the visitor and highlights important customer behavior and insights.

Cost: Free

3. Qualaroo -- Survey your users

Qualaroo was created by Sean Ellis who first coined the term "growth hacking." The tool allows you to easily incorporate surveys on your site during specific points of the user experience. For example, you can set up a pop-up question (that appears in the bottom right corner) to ask why a user leaves or doesn't take a certain action (like not subscribing, or opting into a trial). You can use the insights to make your product even more useful for your users and customers.

Example of a Qualaroo survey

Cost: $63 to $499 per month

4. Optimizely -- test out ideas

Once you have an idea, you may want to run an A/B test, where you compare two versions of your site or web page: "A" will be the current version and "B," the version with the new idea, be it a new feature, functionality or layout. Typically, the experiment will entail showing a random 50 percent of your visitors version A and the other 50 percent, version B. It then will track which does better in terms of criteria like getting more users, getting more people to buy something or getting users to stay longer on the site.

Optimizely is one of the best tools for A/B testing. You can quickly run A/B experiments without the need to know any coding. Experiments can be run across a desktop, mobile site or mobile app. The first time we used it, we were surprised at how easy it was to configure different versions of a web page like a homepage or a landing page, run the experiment and track the results.

Cost: $49-plus, based on traffic

Related: Growth-Hacking 101

5. Usertesting -- get video feedback of your product from target users

If you're making a change to your website or adding a new functionality or tool, it's a good idea to get feedback before rolling it out. Usertesting makes it easy to get feedback from a large number of users -- over 1 million, to be exact. You can target a select set of users based on demographics like gender, age, income, geography and web expertise. Typically, you get user feedback within an hour of a submission.

Cost: $49 per video

6. ListBuilder -- collect emails from site visitors

Building an email list of your visitors gives you a channel to build a long-term relationship. If you have something of value you can offer in return for people's email addresses, ListBuilder will be an easy tool for you to configure how and at what point during the user experience you should ask for email addresses. (ListBuilder was the brainchild of Noah Kagen, the first marketing head at Mint.com, which was acquired by Intuit for $170 million.)

For example, you can offer your users an ebook or pdf download providing content that's value-add and original. The "carrot" we offer users is notification of a new study we've published (insights about car trends and research). We use ListBuilder in conjunction with aWeber, which is an email marketing solution (starting at $20 per month). The combined tools make it easy to tailor the emails we send.

Cost: Free

7. Yesware -- track emails sent

One of our key marketing objectives is to continually get our name out there. To do that, we conduct data-driven analyses and studies of the automotive industry and reach out to reporters and influencers. That requires a lot of emails. Yesware helps us to track who has opened emails, how many times and for how long. These metrics not only help us decide how to follow up but give a good picture of our effectiveness and success rate for a particular campaign.

Cost: $12-plus per month

8. Tribeboost -- increase Twitter followers

As a startup, you may find it hard to build and continually grow an audience. Tribeboost can help you establish an audience on Twitter. It uses a combination of computer algorithms and human helpers to find Twitter followers. It does this by monitoring Twitter in real time based on keywords and hashtags that you the user specify. You can also narrow your target followers by their location and profiles. Tribeboost's customer service is also first-rate in working to help you home in on your desired set of followers.

Cost: $129-plus per month

Read This: Growth Hacker Marketing: A Primer on the Future of PR, Marketing, and Advertising by Ryan Holiday | Amazon | eBooks.com | Barnes & Noble

BONUS: Mixrank -- build a list of prospective customers

If your company sells to other businesses, Mixrank is a powerful tool for finding potential customers. Its solution allows you to search through millions of companies and the contacts within those companies, using a number of filters. For example, you can find prospects by the type of software they use on their websites, by the type of mobile apps and by their method of online advertising.

Cost: $500-plus per month
In a quest to grow our business, we have tried many ideas; most did not produce the results we wanted... but a few did. And the tactics that have been successful have driven most of our company's growth. We continue to fine-tune and scale those few ideas and try new ones. In the process, we'll probably come across other tools that will become essential in our growth-hacking toolbox. Hopefully, you will, too.