Terms of service

Last updated 1 October 2026.

These terms govern your use of MAC Address Lookup, including this website, the downloadable data files, and the MCP server at https://mac.jasontally.com/mcp. By using the site you agree to them. If you do not agree, do not use the site.

In these terms, the Operator means the individual or legal entity that publishes and operates this site, and the people acting on its behalf. Where the Operator is a legal entity, you are contracting with that entity alone. Where the Operator is an individual, that individual is the party, and this site is not operated by or on behalf of any other party.

The service, and what it is not

The site resolves a MAC address or an OUI prefix to the organization that holds the matching block in the public IEEE Registration Authority registries. That is the whole service. It is a reference lookup for people who work with networks.

It is not an investigative tool. It does not identify a person, a device owner, a subscriber, or a user. It does not tell you who is behind an address on a network, whether a device is yours, or whether anyone is doing anything unlawful. A prefix resolves to a registered organization; the IEEE registries say nothing about the individuals who use hardware from that organization, and you must not treat a result as evidence about any person.

No warranty: read this before relying on anything

This site is provided as is and as available, with no warranty of any kind, express or implied, including but not limited to warranties of accuracy, merchantability, fitness for a particular purpose, and non-infringement.

You accept that, in particular:

• Results may be wrong, incomplete, or out of date. The registries are public and change without notice. A prefix can be reassigned, transferred, or retired, and the name on a block can be wrong for years after a company is bought. A result of "no match" means no match in the dataset, not that a block is unassigned.
• Absent results are expected, not exceptional. Modern phones randomize Wi-Fi addresses, virtual machines and manual assignments use locally administered ranges, and private addresses are common on real networks. A randomized address normally has no registered organization, and the site will say so rather than guess.
• Ownership dates are observation dates. A date shown for an ownership change is when the change was first seen in public data, not a legal transfer or assignment date.
• Availability is not promised. The site is a volunteer project with no uptime commitment and no service level.

Do not use this site as your only source, and do not use it to make a decision with legal, security, financial, employment, or disciplinary consequences. If a vendor identification matters to you, confirm it against the IEEE registry directly, against the manufacturer's own documentation, and against your own network records before you act on it.

No affiliation with IEEE

This site is an independent, unaffiliated project. It is not endorsed by, sponsored by, or associated with the IEEE or with the Institute of Electrical and Electronics Engineers, with any organization named in the registry data, or with any vendor whose name appears in a result. "IEEE", "IEEE Registration Authority", and the registry names are used only to identify the public data source, and any trademarks in them belong to their respective owners.

A result naming an organization is a statement about a public registry entry. It is not a statement by that organization, an endorsement of it, or a claim about its products.

Licence for the code and the data

The site's source code is published under the MIT licence. The registry data is public IEEE data; the ownership-history data comes from runZero mac-tracker under the MIT licence. Third-party components keep their own licences, which are listed in the site's licence notice.

You may read, download, and reuse the data files. These terms grant you no trademark rights, no rights in any organization's name, and no permission to imply that this project or any listed organization is affiliated with you.

Acceptable use of the MCP endpoint

The MCP endpoint is open, unauthenticated, and free. That is a deliberate choice, and keeping it that way depends on everyone using it reasonably. Do not:

• send automated traffic at a rate that degrades the service for others;
• attempt to overload, probe for a vulnerability, bypass a limit, or disrupt the service;
• use the endpoint, or this site, to identify, track, profile, or gather information about any individual, household, or device owner;
• use a result to make an accusation, or to harass, discriminate against, or misrepresent any person or organization;
• resell access to the endpoint, or present it as your own service.

You may cache the static data files. Please do not build a competing service that mirrors this endpoint commercially; if you want the dataset at scale, download the files instead.

These limits may be enforced at any time, including by refusing requests or blocking an address range, without notice.

Your responsibilities

You agree that you are responsible for your own use of the site, including:

• complying with these terms and with applicable law;
• obeying the licences of the IEEE and any other data you retrieve, and respecting the rights of the organizations whose names appear in the data;
• keeping any credentials, tokens, or keys you use to reach the site confidential, where you have any;
• not relying on the site for any decision that could cause you or someone else harm if it were wrong, as set out above.

Intellectual property and content

The site's own code, design, page text, and generated page layout belong to the Operator and are covered by the MIT licence. Organization names and addresses in the registry data belong to their respective owners and are reproduced here as public registry facts. A MAC address prefix is a number; it is not a trademark, and no vendor endorsement is implied by its appearance.

Third-party links

The site links to the IEEE registries, to runZero mac-tracker, to bundled-software repositories, and to records hosted elsewhere. Those sites are operated by others. This project does not control them and is not responsible for their content, their availability, or their privacy practices.

Privacy

The privacy policy describes what the site does and does not collect. It forms part of these terms. In short: browser lookups run entirely on your own device, the site sets no cookies and does no tracking, and the one place where a lookup leaves your device is the MCP endpoint, which is described there in full.

Limitation of liability, including negligence

To the fullest extent permitted by applicable law, the Operator is not liable for any indirect, incidental, special, consequential, exemplary, or punitive damages, and for any loss of profits, revenue, data, goodwill, or business opportunity, arising out of or related to your use of the site, however caused and even if the possibility of such damages was known.

The Operator is not liable for ordinary negligence. To the fullest extent permitted by applicable law, that includes any claim that the site, the data, or a result was inaccurate, incomplete, out of date, unavailable, or unsuitable for your purpose, and any claim that a failure, delay, or error in the site caused you loss. Ordinary negligence means a failure to exercise reasonable care. You accept that risk and release the Operator from it.

The cap. To the fullest extent permitted by applicable law, the Operator's total liability to you for all claims arising from the site is limited to the greater of the amount you paid to use the site, which is zero, or one hundred US dollars (100 USD).

What this does not do. Nothing here excludes or limits liability that cannot lawfully be excluded or limited. The release of ordinary negligence does not reach gross negligence, willful or intentional misconduct, fraud or fraudulent misrepresentation, or a violation of law. Those are not waivable, and this section does not pretend otherwise: a clause that claimed to waive them would be unenforceable in whole or in part, which would put the rest of the cap at risk as well. the law treats this as the boundary of what an agreement can do.

Some jurisdictions, and some circumstances, do not permit a limitation of liability toward a consumer at all, and a court may decline to apply this section in full or in part. Nothing in this section is a representation that it will be enforced.

No professional advice

Nothing on this site is legal, compliance, security, or forensic advice. A registry match is a fact from a public dataset, not a conclusion about a device, a network, or a person. Consult a qualified professional before acting where the law or your obligations require it.

Indemnity

You agree to indemnify, defend, and hold harmless the Operator from any claim, demand, loss, or expense, including reasonable legal fees, arising out of your use of the site, your breach of these terms, or your violation of any law or the rights of a third party. This obligation applies to the fullest extent permitted by applicable law. It covers third-party claims; it does not limit the limitation of liability in this document, which applies to your own claims too.

Changes to these terms

These terms may change when the site changes, so that they continue to describe it accurately. The date at the top of this page always reflects the current version. Continuing to use the site after a change means you accept the updated terms. If you do not accept them, stop using the site.

Termination

You may stop using the site at any time. The project may change, suspend, or discontinue any part of the site, including the MCP endpoint, at any time and without notice. Sections that by their nature should survive termination, including the no-warranty, no-affiliation, liability, and indemnity sections, do survive it.

Governing law and venue

These terms are governed by the laws of the State of Florida, United States of America, without regard to its conflict-of-law rules. This choice governs the interpretation of these terms and the construction of the agreements in them. It does not deprive you of any mandatory consumer protection of the country or state where you live or where you use the site, and it does not limit the right to bring proceedings in the courts of your own country or state where that right is mandatory.

The Operator and you will each try to settle any dispute informally first, by raising it on the public repository named in the Contact section. If a dispute is not settled that way, and to the extent the law allows a court to hear it, the state and federal courts located in the State of Florida have exclusive jurisdiction over it, and each party submits to that jurisdiction.

Nothing in this section limits any right you have to bring a claim where you live, to the extent that right cannot be waived. If any provision of these terms is held unenforceable, it will be enforced as far as the law allows, and the remaining provisions stay in force. These terms are written in plain English; the English text governs if a translation differs.

Contact

Questions about these terms, or a problem with the site, can be raised on the public repository, which is linked from the help page. Because the site has no accounts, no support staff, and no published contact address, that repository is the only official route to the Operator and the fastest place to get a response.

The lookup methodology, data sources, and machine-readable downloads are documented on the help page.