theHarvester: how to use it, and what it is for
theHarvester collects hostnames, email addresses, IPs and URLs for a domain from public sources. It is a classic first step in authorized security assessments, and it answers a different question from a username search. Here is how it works.
Domain reconnaissance. Project: github.com/laramies/theHarvester · License: GPL-2.0 · Last reviewed 2026-10-13
What is theHarvester?
theHarvester, created by Christian Martorella (laramies), is open source under GPL-2.0. It gathers data about a domain or organization from search engines, certificate transparency logs, DNS datasets, code repositories and threat intelligence platforms, then normalizes hostnames, emails, IPs, URLs and ASNs.
Recent versions need Python 3.14 and the uv package manager. Besides the CLI there is HarvestView for reviewing local run history and evidence, and a REST API. The README says to run it only against targets you own or have explicit permission to test.
How to use theHarvester
- Install uv, then clone the repository and sync its dependencies.
- Run theHarvester with -d for the domain and -b for the sources to query.
- Use -h to list all sources and output options.
- Only scan domains you own or have written permission to assess.
Example commands from the project's README (check it for the current version):
git clone https://github.com/laramies/theHarvester.git
cd theHarvester
uv sync
uv run theHarvester -d example.com -b crtsh,certspottertheHarvester vs WhatsMyName Apps
| Feature | theHarvester | WhatsMyName Apps |
|---|---|---|
| Starts from | A domain or organization | A username (up to 5 at once) |
| Finds | Hostnames, emails, IPs, URLs, ASNs | Profiles at that username across 3,166 sites |
| Domain data | Subdomains and related hosts | Registration status for seven endings via RDAP |
| Setup | Python 3.14 and uv | Nothing to install. It runs in the browser |
| Automation | CLI and REST API | No API and no CLI |
| Price | Free, open source | Free, no sign-up |
Based on theHarvester's own documentation as of 2026-10-13. Tools change; the project page is the final word.
Pros and cons of theHarvester
Pros
- Fast way to map a domain's public footprint.
- Many passive sources, including certificate transparency.
- CLI, local evidence viewer and REST API.
Cons
- Domain-focused; it does not search usernames.
- Needs a recent Python and uv; some sources need API keys.
- Only appropriate for authorized assessments.
Who theHarvester is for
theHarvester is for security professionals mapping an organization's attack surface with permission. If your question is "where is this username used?", it is the wrong tool and a username checker is the right one.
Try a username search in your browser
Free, no sign-up. Checks 3,166 sites; the username is not stored or logged.
Frequently asked questions
How do I install theHarvester?
Install uv, clone the GitHub repository, run uv sync, then run uv run theHarvester -d with your domain and -b with the sources you want.
Can theHarvester find usernames?
No. It works from a domain and collects hostnames, emails, IPs and URLs. Use a username search tool to find profiles for a handle.
Is it legal to run theHarvester?
The project says to run it only against targets you own or have explicit permission to test. Get written authorization before any assessment.
Related tools and guides
- SpiderFoot: OSINT automation framework
- Recon-ng: Web reconnaissance framework
- OSINT Framework: Directory of OSINT tools
- Holehe: Email account enumeration
- All OSINT tools compared
- OSINT username search · Reverse username lookup · Platform username checkers
- Username OSINT for beginners
Names and trademarks belong to their owners. WhatsMyName Apps is independent and not affiliated with or endorsed by theHarvester or its authors.