Logbook of the World (LoTW) is a web-accessed database provided by theAmerican Radio Relay League (ARRL) to implement a contact verification service amongamateur radio operators. Using LoTW, radio amateurs (hams) are able to claim and verifycontacts (QSOs) made with other amateurs, generally for claiming credit for operating awards, such asDXCC. Previously, hams had to rely on paperQSL cards and submit to ARRL; a slow and somewhat expensive process. LoTW began operation in 2003.[1]
The LoTW system uses "secure" authentication usingcryptographic key distribution. An amateur's computer-based logbook, in ADIF[2] or Cabrillo[3] format, have to be "signed" using a key obtained from ARRL. (Logbook data includes callsigns and locations of stations, contact time, frequency, and operating mode.) ARRL assigns such keys to amateurs who appear in theU.S. FCC licensing database or to non-US amateurs who provide alternate proof of identity.
Once a log file is signed using ARRL's "TrustedQSL" (or equivalent) program, it is uploaded to the ARRL server and entered in the database.
Log records in the LoTW database are automatically compared so that when a contact at a particular time, operating mode, and frequency band is claimed by both participating amateurs (both of whom must have submitted their logs), a "QSL" (confirmation) is declared for a later award claim, e.g., for contacts with all U.S. states or 100 different countries. The matching process is blind, meaning that neither of the two stations can see pending confirmations before they uploaded a matching record. The LoTW QSL is purely electronic; there are no paper confirmations. However, a participant is able to print out a record of each confirmed contact, complete with its LOTW record number.
A LoTW-registered amateur is able to log into the LoTW website to view their logged QSOs and the verified QSL matches. When the amateur obtains a sufficient number of LoTW and/or traditional paper QSLs, they are able to apply for an ARRL award. As of January 2012, LoTW credit could be used for credit for awards issued by the ARRL and byCQ Magazine. The ARRL does not recognize other web-based QSL systems, such as eQSL,[4] for awards credit.
As of May 26, 2022 the LoTW server[5] provided the following information:
| 1,527,031,336 | QSO records have been entered into the system. |
| 329,084,756 | QSL records have resulted. |
| 159,231 | Users are registered in the system |
| 227,651 | Certificates are active |
| 55,553,189 | User files have been processed |
| 21.6% | Percentage of submitted QSO records confirmed as QSL records |
All registered LoTW users have access to the main user data site:lotw.arrl.org. The TrustedQSL software for certificate management and logbook signing is available through the main LoTW information site:www.arrl.org/logbook-of-the-world. Versions of this software were available for many versions of Windows, Macintosh, and Linux operating systems.
Programmers' information and source code are available attrustedqsl.sourceforge.net, in particular the2001 design specification.
LoTW functions are integrated into a number ofamateur radio logging software packages, simplifying the signing and upload process.
On May 16, 2024, the ARRL announced that it was responding to a "serious incident involving access" to its network and headquarters-based systems. This incident resulted in access to Logbook of the World being unavailable.[6] According to one source,[7] the incident is of cyberattack nature.