Find Prior Art: 15 Free Patent Databases, AI Tools, and Search Engines

Image: Free Databases and Tools for Patent Search

According to a study, 70%–90% of technical knowledge is found in patents, and moreover, it is not published elsewhere except in patents.

So, if you happen to be a professional in a technical field, you may be missing out on a lot but not anymore. You are in the right place. Welcome!

Imagine if you are a Ph.D. student fully engrossed in your research and suddenly, you find out that more than 70% of technical literature including futuristic developments is already available which you didn’t even know, or worse, you wasted your time working on the problems already solved in patents.

You may be a student looking to file patent for your college project and can’t afford a prior art search from professionals. In that case, you can perform the prior art search yourself because it is more costly to hire a patent professional than to file a patent at a patent office.

Moreover, learning to search prior art using free patent search engines can help you refine your project and increase your understanding of the topic.

Whether you are an inventor, researcher, entrepreneur, professor, student, professional, etc., Knowing how to find a prior art is always a plus.

So, what are those free databases and tools that can be used for patent search?

Free patent search engines and databases are Lens, PQAI, DEPATISnet, Google Patents, free patents online, Google Scholar, Patentscope, Espacenet, inPASS, USPTO PPUBS, JPO, CIPO, Israel Patents Online, AusPat, KIPRIS. These tools provide powerful features like artificial intelligence, machine translation, etc.

If you are a technical person working in advanced technologies, you should be aware of these.

Before we get into the list, we want you to know that we have written a DIY guide for you: Prior Art Search Free Guide 101: Do it Yourself

We will look for these free databases and tools for patent search in the coming sections of the article in detail. So sit back, grab a cup of coffee, and let’s dive into a knowledge enhancement session.

1. Lens


It is a free, open-source search tool and database that provides free access to patents and scholarly publications. You can access it here:

If you are a researcher, innovator, student, or even a person with curiosity, you can use this search engine for easy access to patents and prior art.

Apart from being free, the best thing about this platform is that it provides various tools to analyze and visualize the results for each search query.

Visual representation of patent data shows the key players in the technology; publication, granted, filing trends over time; legal status of the patents; jurisdictions of documents; top CPCs; top inventors; top agent & attorneys; top cited documents; document type of retrieved results of a search string.

The database’s 144.3 million patent records make it one of the most widely covered databases.

Although both Google Patents and Lens are user-friendly, Lens provides more functionality compared to Google Patents. I’d say that searching on is more of a visual treat

2. PQAI: patent quality through artificial intelligence


This is one of the first AI-based patent search engines that you can leverage in your project. You don’t have to worry about finding documents, classes, or keywords. This engine tool has got it covered all. What makes it unique is that you can talk to it.

By talking, we mean, you can tell this finder tool about your invention in simple text form. Based on its learning and understanding abilities, it will give you prior art documents for novelty and obviousness.

Give this tool a description of a feature, and it churns out probable CPCsgroup art units, and technical concepts. Similarly, give it a keyword or technical concept, and it suggests related keywords or synonyms.

You can play around with this tool at this link:

In combination with chatGPT, this can be a great tool for AI-based patent search. We have explored this possibility in this blog post with live examples.

When it comes to AI, there are multiple tools for different tasks. For example, PQAI can look for prior art documents when it is provided with a summarised invention in one or two sentences.

At the same time, we know, chatGPT does a great job summarizing a patent claim and it getting better day by day.

In fact, we tested our hypothesis (refer to the article below) that if we first summarize a claim, abstract, or embodiment using chatGPT and then provide the summarized version to PQAI, we can get relevant results. And the conclusion is that it worked.

We encourage you to test out such creative use cases of AI.



This patent search engine and database offered by the German Patent Trade Mark Office (DPMA) is free to use and has access to over 135 million data records from more than 100 countries, including European and PCT patents and applications.

You can use this search platform for advanced search capabilities as well.

For example, you may use keywords, inventor, assignee, classes, various dates, etc. to filter the patent results.

It also provides access to full patent texts and their images. In addition to patents, this search engine also provides information about trademarks, utility models and designs, etc.

Whether you are a casual user or a professional patent searcher, this tool with a vast wealth of knowledge is free and available to you.

It offers both German and English interfaces with multiple search options.

You can use six different search modes, namely Basic, Advanced, Expert, Ikofax, and Family.

You can use bibliographic data such as title, abstract, applicant, or inventor, etc. for searching patent documents.

Other salient features of this tool are:

1. Quick search in header,

2. Configuration and sorting in the list of retrieved results,

3. Multiple download options,

4. Facility to use search operators and wildcards for a rich search query,

5. Facility to refine retrieved results in Advanced, Expert, and Ikofax search modes,

6. Tabular format to show bibliographic data clearly,

7.  Facility to search in a full-text mode in English (EP, USA), German(DE), and WIPO (German, French, or English) publications,

8. Facility to show and print documents at different quality levels,

9. Rich navigation throughout display and documents including scrolling,

10. Facility to search using IPCs and catchword index,

11. Interface: German and English,

12. Link to DPMA register to find out the status of files at the DPMA since 1988,

13. Link to the INPADOC families of German and foreign documents obtained from the EPO,

So, overall, having a rich, free patent search engine and database is a blessing.

4. Google Patents Search Engine


It is the most widely used patent search engine because it is easy to use, smart, freely available, and has the backing of Google itself.

With the breakthrough in AI, it is only going to get better. I hope it remains a free patent search tool.

You may be surprised to know that it has also started to search for non-patent literature.

If you are an innovator who is curious enough to delve into the world of patents to understand the future of technology but has limited resources, Google Patents is one of the best places to be.

Searching via the Google Patents Search tool is not difficult at all. In fact, you can simply go to and start searching right away. After all, we have been using Google for web searches for decades, so using a Google product comes naturally to us.

Since we are not talking about simple web searches, you need a little bit of training to get started, however, if you are familiar with patents, then it should be easy for you.

We have written a comprehensive guide, keeping in mind the needs of a beginner and those who are not so familiar with Google Patents. This guide explains how to use Google Patents to your advantage in a detailed and easy-to-understand fashion.

5. Free Patents Online (FPO: Driving IP Forward)

Free Patents Online

FPO provides quick and expert search features that you can utilize to your advantage. You can access this tool at this link:

Quick Search

When it comes to the quick search, you have the facility to use the following fields:

Number Field (Document number, Application Number)

Common Fields (All, Title, Abstract, Claim(s), Description/ Specification)

Date Fields (Filing Date, Publication Date, Foreign Priority)

Classification (Current US Classification, international Classification)

Inventor Fields (Inventor, Inventor Country, Inventor State, Inventor City)

Assignee Fields (Assignee, Assignee Country, Assignee State, Assignee City)

References (Domestic References, Foreign References, Other References)

Legal/ Prosecution Information (Parent Case information, primary Examiner, Assistant Examiner, attorney, or Agent)

The data coverage of this tool is from US patents and applications, EP documents, abstracts of Japan, WIPO (PCT), and German patents (Beta).

Other features available in the quick search are finding documents from the beginning or from the last 20 years; word stemming; and sorting chronologically or by relevancy.

Expert Search

In the expert search, you can enter the search query directly and for the same, field abbreviations and corresponding syntax have to be used.

For example,

ABST is an abbreviation for abstract and is used as follows: ABST/bluetooth to search for Bluetooth in the abstract.

You can find these abbreviations and their syntax on the search page itself, so there’s no need to worry much about that.

6. Google Scholar Search Engine


Google Scholar came into existence only to avoid duplication of work in different parts of the world because people didn’t know the developments happening elsewhere in their domain.

It has evolved a lot since its inception in 2004. It is a great tool to search for patent and non-patent literature. It doesn’t provide rich functionalities like Google Patents or Lens or paid patent databases, however, it is powerful enough to give you highly relevant documents if you know how to use it to your advantage.

Using our experience with this search engine, we decided to pen down a complete guide on Google Scholar so that you can exploit it to your advantage. You may want to check it out:

7. Patenscope


Run by WIPO, this search engine is widely used around the world and is free of charge. It provides access to international PCT applications as well as the patent documents of member states. 

What makes this tool attractive is that it is powerful yet can be used from your mobile phone. You can search using patent documents using search fields like title, abstract, inventors, applicants, etc.

You can further narrow down your search results to specific groups and sort them by date or relevance.

It provides intelligent and actionable information to inventors, researchers, companies, policymakers, businessmen, and even casually curious individuals in an easy-to-use fashion.

In this CPC browser, you can easily find a close or perfect CPC for the feature in question.

One of the features you’d like is that for each query and its retrieved results, it displays analysis in a tabular and visual format. This analysis consists of information about top countries, applicants, inventors, IPC codes, and publication years.

You can also get machine translation of non-English documents using this tool.

Another useful AI-based tool provided by the WIPO is IPCCAT, which intelligently gives you IPCs if you provide it with the text of an invention or its features.


Another great tool for searching is Espacenet, provided by the European Patent Office free of charge. It boasts of having more than 140 million patent documents in its database from around the world.

You can use this tool to:

Find patent publications,

Get machine translation of documents,

Study trends of upcoming technologies,

Study competitor landscape,

Find innovative solutions to technical problems,

It provides a smart mode and an advanced mode of search. In advanced search, you can search using the English, German, and French languages.

When it comes to using fields, it provides,

Text fields (including title; abstract; description; claims; title or abstract; title, abstract or claims; all text field),

Name fields (including inventors; applicants; inventors or applicants),

Date field (publication date),

Number fields (including priority number; publication number; application number; all numbers),

Classification fields (IPC; CPC; CPC C-sets; IPC or CPC), Other fields (cited documents).

Further, it provides, ‘AND’, ‘OR’, and ‘NOT’ operators among others.

It also provides many proximity options to enhance the quality of retrieved results.

Once you retrieve results, you can choose how to view them, download them in various formats, and sort them by relevancy, publication date, priority date, etc.

Since Cooperative Patent Classification (CPC) has been jointly developed by the European Patent Office (EPO) and the United States Patent and Trademark Office (USPTO) and is based on the former European Patent Classification (ECLA) system, Espacenet provides a CPC browser for the public to use.

Note: Since ECLA was a specific and detailed version of the International Patent Classification (IPC) system, CPCs also relate to IPCs.


This platform for searching Indian Patent documents is provided by the Indian Patent office.

You can access it at:

Using inPASS, you can look for patents, applications, their status, documents or file history, Patent E-register, renewal details, etc.

This has one mode of search including fields such as date, number, name, country, address, IPC, text, filing office, etc. Different search fields are connected using operators such as AND, OR, NOT.

Regarding utilizing various functions of inPASS and searching Indian patent applications, we have written a blog post which you can check out:

10. USPTO Patent Public Search (PPUBS)

USPTO Patent Public Search

This free patent search engine is provided by the USPTO (United States Patent and Trademark Office).

You can access it at:

It has two options for searching:

  1. Basic 2. Advanced.

Basic search

If you are new to patent search or you want to search patents by keywords, or common search fields like applicant or publication number then you can use Basic search.

It is similar to the structured search of AusPat or inPASS of the Indian Patent Office.

You have different search fields to choose from such as applicant name, assignee name, attorney agent/ firm, attorney name, patent/ application publication number, inventor name, publication date, or everything. Further, you have boolean connectors (AND, OR, NOT).

Advance Search

It provides full query options and further refining options using various filters. The interface of this tool is no less than that of paid databases.

You can learn to build queries and search for US patent documents while accessing notes from the help section right there on the page. It further has the option to refine the search with the “enhanced search” feature.

So, all in all, this can be a great free search engine to search prior arts as most of the technology is by default patented In the US. This increases the chances of finding a relevant document using this tool.

11. JPO IPDL (Japan Patent Office Industrial Property Digital Library)


JPO IPDL is a Japanese platform for patent information available at no cost to users. You can use this to search Japanese patents, patent applications, utility models, designs, and trademarks. It consists of documents since the end of the 19th century.

You can access this search engine on

Originally, it was created and launched by the Japanese Patent Office (JPO) in 1999. Currently, it is provided by INPIT (National Center for Industrial Property Information and Training).

It has three options for search as follows:

Patent/ utility model number search/ OPD:

It has two options to choose from 1. Literature 2. OPD inquiry.

If you choose Literature then you can search for patents/ utility models, foreign literature, and non-patent literature.

However, if you choose the second option i.e. OPD then you can inquire about application/examination-related information (dossier information) held by the patent offices around the world. But for that, you have to choose issuing country/ region/ agency, type, and number.

Patent/ utility model search:

You can search for patents/ utility model publications, foreign literature, and non-patent literature by bibliographic data, abstract, keywords, classification (FI/ F term, IPC), etc.

Patent/ utility model classification search (PMGS):

You can find classes by keywords for the latest IPC and FI/ F terms.

JPO IPDL also provides the facility to search for free trademarks and design search.

12. CIPO’s Canadian Patents Database


This tool is freely made available by the Canadian Intellectual Property Office (CIPO). You can search for bibliographic data such as titles, names, and classifications for Canadian patent documents since 1869.

You can access this tool at:

Among other things that you can search for are:

Text databases (Abstract and claims) are searchable from 1978,

Issue date is searchable from 1869,

Filing date is searchable from 1978,

Priority date is searchable from 1989.

On the introduction page, this database boasts of providing access to more than 2.5 million patent documents.

It has 4 features for search namely:

Basic Search

useful for basic text search to find patent documents having searched word or phrase

Number Search

useful for finding a specific patent document using its number

Boolean Search

useful for searching multiple text fields in combination with boolean operators (AND, OR) to narrow down or broaden the scope of the search

Advanced Search

Useful in searching for complex queries. In this feature, you can input multiple texts in any of the search field (title, claims, abstract, description, inventor, current owner, owner on record, applicant, IPC, CPC, PCT filing no., international publication number).

Moreover, you can input inventor’s country or territory, select the status of the patent (all, active, patents, pending applications, public domain), type of patent document filing (PCT or Non-PCT document), language of filing (English, French), license availability (yes, no), date type (issue date, file date, examination request date, open to pub. Insp. Date, priority date, national entry date).

13. Israel Patents Online

Israel Patents Online

For patent documents from Israel Patent Office, you can search freely on Israel patents online at:

It has a simple text-based search and advanced search options.

Advance search

you can search for agent, applicant OR inventor, applicants, application number, application status, claims, CPC classification, description, event date, even publication date, event type, extension expired date, family application, filing date, filing year, full text, granted date, inventors, IPC classification, legal proceeding status, next renewal date, patent expired date, patent extension status, PCT number, priority application number, priority country code, priority date, submission date, title, update date, WO publication number.

Moreover, you can use search conditions such as ‘ANY’, ‘ALL’, ‘NOT’ which are similar to boolean connectors ‘OR’, ‘AND’, ‘NOT’ respectively.

After running the query, you can also sort the retrieved results by relevance, filing date, update date, and application number.

After you have run your query, you can save it for future reference.

14. AusPat (IP Australia)

IP Australia

This free search engine & database is provided by IP Australia to search for Australian patent documents.

You can access this at: 

It has three options for search:

1. Quick 2. Structured 3. Advanced

Quick Search

You can directly enter a patent or application number, invention title, applicant, inventor, agent, WIPO number, PCT number, filing date, application status, earliest priority date, first IPC mark, and abstract in the search box. After the results are retrieved for input, you can refine your query, customize the view, and download the application numbers of the search results.

Structured Search

it is similar to inPASS of the Indian Patent Office when it comes to the user interface. In this, you have multiple search fields that can be connected using boolean operators (AND, OR, NOT). Along with the search boxes, it has [?] to provide help with syntax right there on the page.

Advanced Search

In this option, you can directly input the complex search string for search. Construction of these search queries is possible with the help of operators:

What does it do?
ANDexample TI:(photoelectric) AND DS:(Bluetooth) 
searches for photoelectric in title and Bluetooth
in full description
NOT example TI:(“solar cells”) NOT CS:(solar) searches
for “solar cells” in title without “solar” in claims.
ORexample TI:(photoelectric) OR DS:(bluetooth)
searches for photoelectric in title, or bluetooth
in full description or both
TO example  FD:(2005-01-04 TO 2005-01-12)
searches for patent documents having filing
date between these two dates.
*this wildcard replaces zero or more characters.
For e.g., photo* will search for photograph,
photography, photogenic, etc
? This wildcard replaces one character.
For e.g., car* will search for cars
()To make query, as we have seen in previous
/n/it means within n words of
e.g., CS:(“black /5/ white”) searches for
white within 5 words of black in claims.

This tool for searching Korean patent documents free of cost is provided and managed by Korea Institute of Patent Information (KIPI) on behalf of KIPO.

For your information, KIPO is Korean Intellectual Property Office.

Regarding searching, Korean patent and utility documents can be found using full-text search in the Korean language and abstract search in the English language.

These Korean Patent Abstract (KPA) are Korean-to-English translated abstracts, summarized by subject experts, and consists of essential features of the invention from Korean patent documents.

Just like any other tool from other patent offices, it has search operators but with little difference. In other search engines, we directly use boolean logic such as AND, OR, NOT, etc. But in KIPRIS, there are signs for these logics. See the table below for examples and more context.

OperatorOperator signExample
PHRASE” ““phone camera”

You can access KIPRIS for search at:

In case, you have to search non-English prior art, KIPRIS stands out with its machine translation ability to translate “Korean to English”, “English to Korean”, “Japanese to Korean” and “Chinese to Korean”.

When you enter English keywords, the retrieved results show both English and Korean keywords i.e. it provides a cross-lingual search service.

overall, it is useful to know how to use it as a tool to look for non-English documents.


In this, a list of 15 free patent databases, AI tools, and search engines is presented. It is not always feasible to go for paid tools. In such a situation, having such a list in hand is always a plus. The tools we have covered are provided by multilateral organizations, companies, and patent offices of various countries. We have written guides to effectively utilize some of them which you can go through.

We wish you luck in your endeavor to look for patent and non-patent literature to your and your client’s advantage.

Since our aim is to provide patent knowledge and training to everyone who wants to learn, you can browse a wealth of great resources including many guides for free, here: Patents

Sonam Singh

My struggle, in the beginning, made me realize the need to create an ultimate resource that can provide answers to both very basic questions like what, why, when, who, how, where, and the most complex topics about intellectual property. Moreover, my passion for writing and my love for patents made it easier for me to create this super-helpful platform for students, professionals, and curious minds wanting to know about IP. Cheers to that.

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