Recommended free tool combination: Google Keyword Planner (provides search volume ranges such as “1K-10K”) and Google Trends (popularity score 0-100). For paid tools, choose Ahrefs ($99/month, 10 billion keyword database, accurate search volume) or SEMrush ($129.95/month, 140 million keywords + competitor analysis). For long-tail keywords, use AnswerThePublic (limited free queries).
Free Tools (For limited budgets or initial research)
In Google keyword research, free tools provide basic data but have limitations. Google Keyword Planner (requires linking a Google Ads account) gives search volumes as ranges (e.g., “100-1K”) instead of exact numbers, and its competition data is more relevant to paid ads.
Google Trends is free but only shows relative popularity (0–100) and not actual search volume, making it suitable for observing trends rather than quantitative analysis.
Ubersuggest free version allows only 3 queries per day but provides keyword difficulty (SEO Difficulty) and CPC (Cost Per Click) estimates, making it useful for quick reference.
AnswerThePublic excels at finding long-tail question-based keywords (such as queries starting with “how to” or “best”), but the free version shows only partial results — full access requires payment ($99/month).
If you’re on a tight budget, it’s recommended to combine these tools — for example, use Google Trends to find trending terms, Ubersuggest to check search volume, and AnswerThePublic to supplement question-based keywords.
Google Keyword Planner
Google Keyword Planner was originally designed for Google Ads users but can also be used for SEO. Its main advantage is that the data comes directly from Google Search, but its main drawback is that search volume is shown as ranges (e.g., “1K–10K”) instead of exact numbers, making precise keyword comparisons difficult.
Its “competition level” metric is based on ad bidding intensity rather than organic search difficulty, so its SEO relevance is limited.
Still, it provides useful information such as average monthly search volume ranges and suggested bid ranges (CPC), making it suitable for preliminary screening of high-potential keywords. Note that you must register a Google Ads account (no need to run ads) to view full data.
Google Trends
Google Trends is a free trend analysis tool that shows keyword popularity changes over time and by region, but does not provide actual search volume.
Its data is presented as a relative popularity score (0–100), useful for comparing multiple keywords (e.g., “iPhone vs Samsung”). A practical tip is to use the “related queries” feature to see what other terms users are searching for, which helps expand your keyword list.
For example, searching for “yoga mat” might reveal related terms like “non-slip yoga mat” or “thick yoga mat.” Google Trends also supports regional filters, making it ideal for localized SEO — for example, comparing keyword popularity in the U.S. and the U.K.
Ubersuggest
Ubersuggest, developed by SEO expert Neil Patel, offers keyword search volume, SEO difficulty score, and CPC estimates in its free version, but limits to 3 queries per day. Exceeding this limit requires upgrading ($29/month and up).
Its data sources include Google Keyword Planner and third-party crawlers, so search volume data is more specific than Google Trends (e.g., “2,400” instead of a range).
The SEO difficulty score (0–100) helps assess keyword competitiveness but is based on factors like domain authority and backlinks, not actual ranking difficulty.
Ubersuggest also offers a “content ideas” feature, listing top-ranking pages that can be studied for competitor content structures.
AnswerThePublic
AnswerThePublic focuses on discovering question-based keywords that real users search for (e.g., “how to fix a leaky faucet” or “best running shoes for flat feet”), which are often low-competition and ideal for long-tail SEO strategies.
The free version shows partial results, but full access (including search volume) requires payment ($99/month). Its data comes from Google autocomplete and related searches, reflecting real user intent.
For example, entering “coffee machine” might yield “how to clean a coffee machine” or “best coffee machine brand.” These types of keywords tend to have higher conversion rates because users often have a clear intent.
However, AnswerThePublic does not provide search volume data, so it’s best combined with Google Keyword Planner or Ubersuggest for deeper analysis.
Paid Tools (For advanced optimization or business use)
Compared to free tools, paid keyword tools have key advantages such as precise search volume data (e.g., Ahrefs down to single digits), comprehensive competitor analysis (covering organic and paid search), and long-term historical tracking (SEMrush offers up to 5 years of data).
For example, Ahrefs includes over 10 billion keywords, updates search volume monthly, and includes click-through rate (CTR) estimates.
SEMrush covers 140 million keywords and is particularly strong in analyzing competitor keyword strategies, showing top 100 ranking keywords and their traffic shares.
Moz Pro, though smaller (around 500 million keywords), offers a unique “keyword difficulty” score (0–100) to quickly assess optimization feasibility.
Paid tools typically start from $99–130/month and are ideal for teams with consistent content output or advertising budgets.
Ahrefs
Ahrefs’ keyword database includes over 10 billion keywords, with monthly updates and search volume data accurate to the single-digit level (e.g., “2,450 searches/month” instead of a range).
In addition to search volume, Ahrefs provides CTR (Click-Through Rate) data, showing how clicks are distributed across search results (for example, the top result usually receives 30–40% of clicks).
Another core feature is the Keyword Gap tool, which compares keyword overlap among competitors to quickly find missing opportunities. For instance, if three competitors rank for “best wireless headphones” but your site doesn’t, that’s a clear optimization target.
Ahrefs’ Content Explorer can also analyze high-performing content across the web — for example, finding “coffee maker” articles that gained the most backlinks in the past year — providing inspiration for content creation.
However, Ahrefs has a higher starting price ($99/month) and may be complex for beginners, making it better suited for professional SEO teams or long-term content marketing efforts.
If interested, read: What Ahrefs Is Used For | $129/$249/$449/$14990 Plan Guide
SEMrush
SEMrush’s keyword database covers 140 million keywords and provides the Keyword Magic Tool, which can generate hundreds of long-tail variations in one click (for example, searching “running shoes” returns “best running shoes for flat feet” or “women’s running shoes 2024”).
The Competitor Keyword Analysis feature is particularly powerful, allowing you to view a competitor’s top 100 ranking keywords and their estimated traffic share. For example, analyzing a fitness equipment site might reveal that 30% of its search traffic comes from “home gym equipment” keywords, indicating an opportunity to target similar terms.
SEMrush also offers Historical Data, letting you track a keyword’s search volume trends over the past 5 years — useful for identifying seasonal patterns or long-term demand shifts.
However, SEMrush’s pricing is slightly higher than similar tools ($129.95/month), and some advanced features (like API access) require more expensive plans. If your budget is limited but you need competitor insights, consider SEMrush’s Guru plan ($249.95/month), which includes batch keyword processing and larger data export limits.
If you are interested in this tool, you can read: Ubersuggest vs SEMrush vs Ahrefs SEO Review丨Features/Data/Pricing
Moz Pro
Although Moz Pro’s keyword database (around 500 million) is smaller than Ahrefs and SEMrush, its Keyword Difficulty (KD) scoring system is more beginner-friendly for small and medium-sized businesses and individual webmasters.
The KD score (0–100) takes into account the domain authority and backlink count of top-ranking pages to quickly assess keyword competitiveness. For example, a KD score below 30 is generally considered easy to rank for, while scores above 70 may require a significant number of backlinks.
Moz Pro’s Rank Tracking feature monitors daily ranking changes for multiple keywords and compares your positions with competitors. Another useful feature is the On-Page Grader, which automatically evaluates a page’s title, meta description, and content structure based on target keywords, then provides an optimization score (e.g., 85/100).
However, Moz Pro’s search volume data is updated relatively infrequently (about once per quarter) and does not include click-through rate (CTR) analysis, making it less suitable for advertisers who require real-time data.
Its starting price is $99/month, comparable to Ahrefs, but its features are more focused on basic SEO.
Keyword Tool
The core function of Keyword Tool is generating massive long-tail keywords based on Google Autocomplete, making it especially useful for SEO research in non-English markets. It supports over 190 languages (including Chinese, Spanish, Arabic, etc.) and displays estimated search volumes from Google Keyword Planner and third-party databases.
For example, searching “coffee machine” may return specific queries like “best home coffee machine” or “automatic coffee machine price,” along with estimated search volumes (e.g., “best home coffee machine” – 1,200 monthly searches). Keyword Tool also provides Questions and Prepositions categories, such as “how to use a French press” or “coffee maker vs espresso machine,” which reflect clear user intent.
However, Keyword Tool’s search volume data is less precise than that of Ahrefs or SEMrush (some terms only show ranges like “<10” or “10–100”), and it lacks competitive analysis features.
Its Pro plan starts at $69/month, making it suitable for content teams focused on multilingual or long-tail keyword research, though data should ideally be cross-verified using tools like Google Keyword Planner.
How to Choose a Tool?
When choosing a keyword research tool, the key factors include budget (free tools like Google Keyword Planner vs. paid tools like Ahrefs at $99/month), data accuracy (ranges such as “1K–10K” vs. exact values like “2,450”), and use case (SEO, advertising, or multilingual support).
For example, if you analyze fewer than 50 keywords per month, a free tool combo (Google Trends + Ubersuggest) may be sufficient.
But if you need to track 500+ keyword rankings or analyze competitor strategies, a paid tool like SEMrush ($129.95/month) with batch processing capabilities is more efficient.
Google Keyword Planner updates monthly, while Ahrefs refreshes its keyword database daily, making it ideal for real-time use cases.
Choose by Budget
Free tools are suitable for limited budgets or preliminary research but come with clear restrictions. For example, Google Keyword Planner only shows broad volume ranges (e.g., “100–1K”) without a Google Ads login, while paid tools like Ahrefs provide exact numbers (e.g., “1,250/month”).
Free tools also have query limits: Ubersuggest’s free version allows only 3 daily searches, while its paid version ($29/month) removes limits and unlocks more data metrics (like CTR estimates).
If your budget is between $50–$100/month, Moz Pro ($99/month) or Keyword Tool ($69/month) are balanced options. If your budget exceeds $100, Ahrefs or SEMrush offer enterprise-grade analytics.
For business users, consider team collaboration costs — for example, SEMrush’s “Business” plan ($499/month) supports 5 users, making it more cost-effective than buying multiple separate accounts.
Choose by Data Needs
If you only need basic search volume, Google Keyword Planner or Ubersuggest is sufficient.
If you want to analyze long-term keyword trends, SEMrush’s 5-year historical data feature is more useful (e.g., to see if “air fryer” is a seasonal keyword).
Moz Pro’s “Keyword Difficulty” score (0–100) is based on domain authority, while Ahrefs’ “Keyword Difficulty” also considers backlink counts of top-ranking pages.
For content teams, Ahrefs shows actual click distribution across SERP results (e.g., the #1 result receives ~35% of clicks), a feature free tools completely lack. For multilingual markets, Keyword Tool supports keyword generation in 190 languages, though its volume data should be verified using Google Keyword Planner.
Choose by Use Case
- SEO Optimization: Prioritize tools with comprehensive competitor analysis, such as Ahrefs’ “Content Gap” or SEMrush’s “Competitive Keyword Analysis.” For example, if 30% of your competitor’s top 10 keywords are missing from your site, you can focus your optimization efforts there.
- Advertising (Google Ads): Google Keyword Planner is essential, as it integrates ad competition data and CPC suggestions. SEMrush’s “Advertising Research” module can also analyze competitors’ ad copies and historical campaigns.
- Content Creation: Tools like AnswerThePublic or Keyword Tool with question-based keyword discovery are more practical. For instance, you can generate long-tail keywords like “how to fix a leaking faucet,” then use Ahrefs to filter those with search volume >500 for content prioritization.
Moz Pro integrates with WordPress plugins for automated on-page optimization, while SEMrush supports Google Analytics import to directly link keywords with actual traffic performance.
