The drug reference
that shows its work.

Sig is a clinical drug reference app for pharmacists on iPhone and iPad. Sig holds 15,497 guideline recommendations, 434 decision trees, more than 1,000 calculators, and dose rules for 405 drugs. Every result names the document and section behind the answer, and Sig works offline with no account.

Sig is written by a Doctor of Pharmacy and published by HARRIS CLINICAL SOFTWARE LLC, an Arkansas company. Sig is built for pharmacists, pharmacy technicians, students, and residents in the United States, not for patients.

Our data show that 51% of the 384 guidelines in Sig were published in 2023 or later, including 76 from 2026. Additionally, bundled content needs no network connection.

For example, a pharmacist checking gabapentin for a 78-year-old man weighing 62 kg with a serum creatinine of 2.2 mg/dL enters the values once. Sig calculates a Cockcroft-Gault creatinine clearance (Cockcroft 1976) of 24 mL/min and returns approximately 200 to 700 mg once daily, citing the Dosage and Administration section of the FDA label.

Sig is a reference that shows its work. Every dose, score, and recommendation in Sig carries the source guideline, FDA label, or table, with a section, page, or table locator. A pharmacist working with Sig can check the source instead of trusting a summary. Sig also runs offline, needs no account, and sends no analytics.

New content is drafted from a verbatim quote of 25 words or fewer, and a machine check rejects any quote not found word for word in the source. For example, where a source needs a number and prints none, Sig says Information Gap Detected rather than borrowing a number from another document.

Our data show that 100% of the 15,497 recommendations name the source section, and 34% also give a page number, as of November 3, 2026.

Additionally, Sig does not license a commercial database. The Drug Interactions tool reads current FDA labeling, assigns no severity ratings, and says so in the app.

Sig is a reference with 384 guidelines and labels holding 15,497 recommendations across 15 specialties. Sig also has 142 conditions, 434 decision trees, more than 1,000 calculators in 30 categories, and 559 curated monographs. Dose Adjustment holds 3,609 rules for 405 drugs. All of the content is stored on the device.

Our data show that 51% of the guidelines were published in 2023 or later, as of November 3, 2026.

First, infectious diseases. Antibiotic selection covers 72 syndromes and 121 organisms, with 1,647 susceptibility breakpoints and 88 expert rules.

Second, pharmacy reference. Pharmacists using Sig get the FDA Orange Book and Purple Book, controlled-substance schedules for all 50 states, and a DEA number check. Pill identification covers 19,925 products, and crush, chew, and split statements cover 643 drugs.

Third, dosing and safety, for example opioid MME, steroid equivalence, tapers, and levothyroxine and warfarin dosing. Sig adds 235 lab analytes, 3,447 counseling points, USP compounding chapters, 310 OTC ingredients, and 3 immunization schedules. Smoking cessation, religious considerations, patient assistance programs, day supply, a Sig Translator, and a live FDA feed of shortages and recalls round out the tools.

Sig is not yet on the App Store or in open beta. Sig will be released once the author is a registered pharmacist, expected after graduation in December 2026, and a TestFlight beta opens first. An email to support@get-sig.app joins the beta and brings word of the day Sig ships.

The waitlist is an email to us and nothing more: no account and no marketing list. Removal is available at any time on request.

To join: (1) send an email to the support address above; (2) accept the TestFlight invitation from Apple on arrival; (3) install the build and send feedback from inside the app.

For example, a beta tester receives an invitation through Apple's TestFlight app and installs the build. Additionally, the beta is free, and a tester can leave at any time by deleting the app or asking to be removed. Our data show the build already holds 15,497 recommendations and 434 decision trees, as of November 3, 2026.

Sig's core reference is planned to be free: monographs, calculators, dose adjustment, antibiotic selection, identification, conditions, guidelines, and the tools. An optional Sig Pro subscription is planned for workflow features such as watchlists and sync. Pricing is not final. Payment would go through Apple, so we would never see a card number.

For example, Dose Adjustment, Antibiotic Selection, the calculators, and the Orange Book are all part of the planned free core. Additionally, any subscription would be managed in the Apple Account settings on the device and could be cancelled at any time, according to Apple's subscription rules.

Our data show what the planned free core already covers, as of November 3, 2026: (1) 15,497 guideline recommendations; (2) more than 1,000 calculators; (3) dose rules for 405 drugs; (4) 559 curated monographs.