Best Free Keyword Research Tool on Reddit: A Step-by-Step Way to Find What Buyers Search

People who search for the best free keyword research tool reddit threads recommend usually hit the same wall: the free options show little data, and the paid ones cost real money. This guide walks through a practical process that costs nothing to start, uses Reddit and Google together, and tells you where a tool actually saves time. It also states plainly what each tool in this guide does and does not do.

The tools covered are Subgrow, Redreach, Reply Guy and Octolens. None of them is a classic keyword database you type a seed word into. They help with a related job: finding the questions buyers type into Google and the Reddit threads where those questions are answered. If you want that, read on.

What you need first

You do not need a paid account to begin. Gather these before step 1:

• Your website URL. Every tool below starts from what you sell.
• Your 3 closest competitors. Several of these tools ask for exactly this, and it is a good habit even if you work by hand.
• A spreadsheet. Columns for the question, the Reddit thread URL, the exact wording people used, monthly search volume (if you have it) and difficulty (if you have it).
• A clear buyer. Write one sentence: who searches, and what are they trying to decide? Developer tools, AI software and self-serve B2B SaaS are the cases where this matters most, because buyers often read Reddit before they sign up.
• About an hour for the first pass.

One caveat. Free keyword data is thin. Threads such as "Free tool for keyword research" in r/SEO, "Best keyword research tool under $50/month" and "Keyword research on a (reasonable) budget" show how often the budget question comes up. The honest answer is that the process below matters more than any single tool, and you add paid data only when the free pass stops being enough.

Step 1: Write down the questions, not just the keywords

Buyers rarely search a bare keyword. They search a question or a comparison. Start with a list of 20 to 30 of them and sort them into four shapes:

• Comparisons: "X vs Y" for you and each of your 3 competitors.
• Alternatives: "X alternative" for each competitor.
• Best-of searches: "best [category] tool", including a "free" variant if you have a free plan.
• How-to searches: the job your product does, phrased as a task.

The examples in Subgrow's material show the pattern well: "claude vs chatgpt", "chatgpt alternative", "best ai chatbot", "claude ai vs chatgpt" and "best free ai chatbot". Three of those five are comparison or alternative searches, which is typical for software.

Put every question in your spreadsheet. Do not filter yet.

Step 2: Search each question on Google and log the Reddit results

This step is free and takes the longest. For each question, search it on Google and note:

1. Whether a Reddit thread appears on the first page.
2. The thread title and subreddit.
3. Whether the thread is recent or old.
4. Whether the thread answers the question or just asks it.

A question that already brings up a Reddit thread on page one is one Google trusts Reddit to answer. That is a strong signal that buyers go there. Subgrow's homepage says it checked three things its own site shows up for on Google and found a Reddit post on the first page for all three, none of them its own. Your results may differ, but expect to see the same pattern for software questions.

Mark each question with one of three labels: Reddit present, Reddit absent, or Reddit present but weak (old thread, thin answers). The last label is where you have the best chance to publish something better.

Step 3: Treat the thread as the best free keyword research tool Reddit has

The threads you logged contain something no volume tool gives you: the exact wording of real buyers. Read the top threads and copy:

• Phrases in titles. People write "is X worth it" or "cheaper alternatives to X", and those phrases become your next searches.
• Constraints. Words like "free", "under $50", "for beginners" or "without the junk" point to variations you might not have listed.
• Objections. What makes people say no to a tool? Each objection is a possible post or page.
• Names that keep recurring. These are the competitors buyers actually consider, which may not match your own list.

Add each new phrase to your spreadsheet as a fresh question and go back to step 2 for the ones that look promising. Two rounds is usually enough to stop finding new angles.

Step 4: Decide whether a tool will save you time

The manual process above works, but it is slow. This is where a tool earns its place. Here is how the four options compare, using only what each site states.

Note what this table does not say: none of these gives you a searchable keyword database. Treat them as ways to find questions and conversations.

Subgrow

Subgrow is a done-for-you service. It researches your website and your 3 closest competitors, then starts with the 3 strongest search questions that fit your product, each shown with monthly search volume and difficulty. The example on its homepage lists "claude vs chatgpt" at 49,500 searches a month with Low difficulty, and "chatgpt alternative" at 22,200 with Medium.

It then turns questions into posts: a how-to, a comparison, a top-10 list or a question for the group. One post goes out a day in a subreddit your brand owns and moderates, such as r/yourbrand. Each post is ready a week early so you can edit or skip it. When the questions are used up, it finds new ones each month.

Limits to know. It is a service, not a tool you query yourself, so you see the questions it picks rather than running unlimited lookups. It is aimed at developer tools, AI-native software and self-serve B2B SaaS. And it is built for publishing in your own subreddit, not for replying in other people's. Reported results on its site include 19 Gemini citations for AppFollow within three weeks, about 10 times more views in Recraft's subreddit than on its blog, and 23 AI-search quotes of two Cube posts from August to October. Those are the company's own figures for its customers.

Redreach

Redreach takes a different route: you give it your website and your top 3 competitors, and it surfaces highly relevant Reddit posts to engage with. Its homepage says no keywords are needed. It also says it can monitor your brand and competitors around the clock, and its listing examples show a relevance score out of 100 for each thread.

It suits you if your plan is to join existing conversations with AI-guided replies. The homepage does not state a price or a free plan in the text provided, so check the site before you plan around it. It finds threads rather than giving you keyword volume.

Reply Guy

Reply Guy works from keywords you select, though its AI suggests keywords for your product when you create a project. It tracks mentions of those keywords, picks recent and relevant posts, and drafts replies that aim to help the original poster and mention your product where it fits.

The free audit is the useful part for this guide: it runs in about 15 seconds with no account and starts from your website. Paid plans start at $49/mo for the Pro plan, which includes 10 keywords and 100 credits a month. Credits are spent per action: a comment it finds for you costs 1, and a reply posted and verified costs 3.

It suits teams who already know their keywords and want help writing replies. It is not a volume-and-difficulty research tool.

Octolens

Octolens is social listening. It tracks mentions of your brand and competitors across Reddit, X, LinkedIn, Hacker News, YouTube, GitHub, podcasts, news, newsletters and review sites, plus forums and app stores. An AI filter scores each mention for relevance, sentiment and intent, and alerts can go to Slack, Linear, Attio, Claude via MCP or a webhook.

It offers a 7-day free trial with no credit card and a 2-minute setup. It suits teams who want to hear what people say about them across many places, which also feeds your keyword list with real phrasing. It is not a search-volume tool, and its homepage frames it around mentions rather than keyword discovery.

Step 5: Score and shortlist your questions

Now cut the spreadsheet down. Without a paid volume source you will not have exact numbers for everything, so score on what you can see:

• Volume and difficulty where you have them. If a tool or service gives you monthly searches and a difficulty label, use them. Low difficulty with solid volume goes to the top.
• Reddit presence. A question with a weak or missing Reddit answer is easier to win than one with a strong, recent thread.
• Fit. Would a person asking this question plausibly buy what you sell? If not, drop it, however large the volume.
• Buying intent. Comparisons and alternatives usually sit closer to a decision than general how-to searches.

Keep a shortlist of 10 to 15. That is enough for several weeks of content.

Step 6: Turn each question into one useful post

One question, one post. Match the format to the question:

• "X vs Y" becomes a comparison that states who each option suits.
• "Best X" becomes a top-10 list.
• "How do I X" becomes a how-to.
• An open debate becomes a question for the group.

Answer the question in the first two sentences, then add detail. If you publish in your own subreddit, you control the posts and the moderation. If you reply in other people's threads, read each subreddit's rules first, since you are a guest there.

Step 7: Measure what Reddit sends you

Keyword work only counts if you can see results. Set up analytics so Reddit visits are labelled and not lost in a general bucket. Subgrow's approach is to set up Google Analytics so visits show as reddit / organic_social; its Writingmate example reported 28 sessions from Sep 18 to Oct 15, 2026. You can do the same tagging yourself. Review monthly, and move questions that earn visits up your list.

Common mistakes

• Chasing volume alone. A high-volume question that no buyer of yours asks wastes posts.
• Searching bare keywords. Software buyers search comparisons and alternatives. Start there.
• Ignoring thread wording. Your own phrasing may not match how buyers write. Copy theirs.
• Treating a listening tool as a keyword database. Mention trackers show conversations, not search volume.
• Posting promotion with no answer. A post that skips the actual question will not hold up in search or be worth quoting.
• Never revisiting the list. Questions run out and new ones appear. Refresh monthly.
• Expecting instant results. Subgrow states that Google can index a post within hours, while AI search starts citing posts after a few weeks. Plan on weeks, not days.

Frequently Asked Questions

Is there one best free keyword research tool on Reddit?

No single answer fits everyone. Reddit threads on the topic keep asking about free and low-cost options, which shows the need is common, but the process in this guide matters more than one tool. Use Google and Reddit threads for free, then add a tool when manual work gets slow.

Do Redreach, Reply Guy, Octolens or Subgrow give keyword volume?

Of these four, only Subgrow's material shows monthly search volume and difficulty, and it does so for the questions it selects for you. The others focus on finding conversations, drafting replies or tracking mentions.

Which of these can I try without paying?

Reply Guy offers a free audit that takes about 15 seconds with no account. Octolens offers a 7-day free trial with no credit card. Subgrow's homepage has a "Start for free" button. Redreach's homepage text provided here does not state a free option.

Why use Reddit for keyword research at all?

Google already sends buyers to Reddit posts, and AI search tools quote them. Threads also show the exact words buyers use, which a volume number cannot.

How long before Reddit content shows up in search?

According to Subgrow, Google can index a post within hours and rank it in the top 10, and AI search starts citing posts in a few weeks. Results vary by topic and competition.