Introduction to the E-utilities

• Please see the E-utilities Introduction video for a brief introduction.
• Please see the Release Notes for details and changes.

The Entrez Programming Utilities (E-utilities) are a set of eight server-side programs that provide a stable interface into the Entrez query and database system at the National Center for Biotechnology Information (NCBI). The E-utilities use a fixed URL syntax that translates a standard set of input parameters into the values necessary for various NCBI software components to search for and retrieve the requested data. The E-utilities are therefore the structured interface to the Entrez system, which currently includes 38 databases covering a variety of biomedical data, including nucleotide and protein sequences, gene records, three-dimensional molecular structures, and the biomedical literature.

Contents

• E-utilities Quick Start
  Created: December 12, 2008; Last Update: October 24, 2018.
  • Release Notes
  • Announcement
  • Introduction
  • Searching a Database
  • Uploading UIDs to Entrez
  • Downloading Document Summaries
  • Downloading Full Records
  • Finding Related Data Through Entrez Links
  • Getting Database Statistics and Search Fields
  • Performing a Global Entrez Search
  • Retrieving Spelling Suggestions
  • Demonstration Programs
  • For More Information
• A General Introduction to the E-utilities
  Created: May 26, 2009; Last Update: November 17, 2022.
  • Introduction
  • Usage Guidelines and Requirements
  • The Nine E-utilities in Brief
  • Understanding the E-utilities Within Entrez
  • Combining E-utility Calls to Create Entrez Applications
  • Demonstration Programs
  • For More Information
• Sample Applications of the E-utilities
  Created: April 24, 2009; Last Update: November 1, 2017.
  • Introduction
  • Basic Pipelines
  • ESearch – ESummary/EFetch
  • EPost – ESummary/EFetch
  • ELink – ESummary/Efetch
  • ESearch – ELink – ESummary/EFetch
  • EPost – ELink – ESummary/EFetch
  • EPost – ESearch
  • ELink – ESearch
  • Application 1: Converting GI numbers to accession numbers
  • Application 2: Converting accession numbers to data
  • Application 3: Retrieving large datasets
  • Application 4: Finding unique sets of linked records for each member of a large dataset
  • Demonstration Programs
  • For More Information
• The E-utilities In-Depth: Parameters, Syntax and More
  Created: May 29, 2009; Last Update: November 30, 2022.
  • Introduction
  • General Usage Guidelines
  • E-utilities DTDs
  • EInfo
  • ESearch
  • EPost
  • ESummary
  • EFetch
  • ELink
  • EGQuery
  • ESpell
  • ECitMatch
  • Release Notes
  • Demonstration Programs
  • For More Information
• The E-utility Web Service (SOAP)
  Created: January 21, 2010; Last Update: January 23, 2015.
  • Termination Announcement
  • For More Information
• Entrez Direct: E-utilities on the Unix Command Line
  Created: April 23, 2013; Last Update: October 21, 2024.
  • Getting Started
  • Searching and Filtering
  • Structured Data
  • Complex Objects
  • Sequence Records
  • Sequence Coordinates
  • Gene Records
  • External Data
  • Local PubMed Cache
  • Automation
  • Additional Examples
  • Appendices
  • Release Notes
  • For More Information