| Investigator Site File | Academic & Science |
| International Students Festival | Academic & Science |
| Imaging Science Foundation | Academic & Science |
| International Student Friendship | Academic & Science |
| Initiative for Smallholder Finance | Business |
| International Selection Fund | Business |
| International Service Fund | Business |
| Internal Security Fund | Business |
| Islamic Scholarship Fund | Business |
| Insuresilience Solutions Fund | Business |
| Ingénierie Sans Frontières | Community |
| Illinois Shakespeare Festival | Community |
| The Information Security Forum | Community |
| Information Security Forum | Community |
| International Sepsis Forum | Community |
| International Space Forum | Community |
| Integrative Strategies Forum | Community |
| Incoming Signal Failure | Computing |
| Internet Security Framework | Computing |
| Indexed Sequential File | Computing |
| Inter System Facilities | Computing |
| Internet Sans Frontieres | Computing |
| Internet Society Foundation | Computing |
| Internet Social Forum | Computing |
| Internet Signal Failure | Computing |
| I Simply Forgot | General |
| Imperial Strike Force | General |
| Interdisciplinary Studies Field | General |
| Initial Submittable File | General |
| Introduction To Structure And Function | General |
| International Shooters Force | General |
| Importer Security Filing | General |
| International Symposium on Forecasting | General |
| Interactive Shader Format | General |
| Intelligent Sensing Framework | General |
| Integrated Semantic Framework | General |
| Infinate Shape Feature | General |
| Internationale Schule Frankfurt | General |
| Insulin Safety Factor | General |
| Ink Serialized Format | General |
| Information Systems Frontiers | General |
| Import Security Filing | General |
| I Shot Foot—a | General |
| Infra Slow Fluctuations | General |
| IASPEI Seismic Format | General |
| Input Serialized Format | General |
| Import Service Fee | General |
| Infinite Shape Feature | General |
| Information Systems of Florida | General |
| Irrigation Service Fee | General |
| Information Strike Force | General |
| Infra Slow Fluctuation | General |
| Interconnected Systems Framework | General |
| Importer Security Filling | General |
| Is Short For | General |
| Intermediate Sanction Facilities | General |
| Intermediate Sanctions Facility | General |
| Instrument Safety Factor | General |
| Infotainment Specification Format | General |
| Intelligent Seat Fold | General |
| Iron Spring Farm | General |
| Ian Somerhalder Foundation | General |
| Israel Science Foundation | General |
| IndoChina Starfish Foundation | General |
| Indochina Starfishfish Foundation | General |
| International Student Foundation | General |
| International Security Foundation | General |
| Islander Sports Foundation | General |
| Institute for a Sustainable Future | Governmental |
| Internal Security Forces | Governmental |
| Internal Security Force | Governmental |
| International Shipping Federation | Governmental |
| The International Shintaido Federation | Governmental |
| International Seed Federation | Governmental |
| International Skyrunning Federation | Governmental |
| Insaf Student Federation | Governmental |
| Immigration Services Funding | Governmental |
| Institute for Sustainable Futures | Governmental |
| Institute for Spiritual Formation | Governmental |
| International School Frankfurt | International |
| International School of Florence | International |
| Inverse Square Factor | Medical |
| Inverse Syndrome Former | Medical |
| In So Far | Messaging |
| Integrated Support-fielding | Military and Defence |
| Iraqi Special Forces | Military and Defence |
| Iraqi Security Forces | Military and Defence |
| Intelligent Strong and Fast | Military and Defence |
| Industrial Space Facility | Space Science |
| International Sports Federation | Sports |
| International Skateboarding Federation | Sports |
| International Snowboard Federation | Sports |
| International Softball Federation | Sports |
| I Sell Fitness | Sports |
| Inclusive Sports and Fitness | Sports |