| Wed, April 1 | April Fools | Multiple [Show] | Observance |
| Wed, April 1 | Cyprus National Holiday | Cyprus | National Holiday |
| Wed, April 1 | April Fool's Day | Multiple [Show] | Observance |
| Wed, April 1 | Investiture Ceremony of the Captains Regent 1 | San marino | National Holiday |
| Wed, April 1 | National Poetry Month | - | Monthly |
| Thu, April 2 | Union Day of Belarus and Russia | Belarus | Observance |
| Thu, April 2 | Day of the Veterans | Argentina | National Holiday |
| Thu, April 2 | World Autism Awareness Day | - | International |
| Thu, April 2 | Pascua Florida Day | United states (Florida) | Local Observance |
| Thu, April 2 | Vietnamese Kings' Commemoration Day | Vietnam | National Holiday |
| Fri, April 3 | Children's Day observed | Taiwan | National Holiday |
| Sat, April 4 | United Nations' Mine Awareness Day | - | International |
| Sat, April 4 | Daylight Saving Time ends | Multiple [Show] | Clock Change/daylight Saving Time |
| Sat, April 4 | Ching Ming Festival | Hong kong | National Holiday |
| Sat, April 4 | Qing Ming Jie | China | National Holiday |
| Sat, April 4 | Yom HaAliyah | Israel | National Holiday |
| Sat, April 4 | Tomb Sweeping Day | Taiwan | National Holiday |
| Sat, April 4 | Children's Day | Taiwan | National Holiday |
| Sat, April 4 | Independence Day | Senegal | Public Holiday |
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| Sat, April 4 | Peace Day | Angola | Public Holiday |
| Sun, April 5 | Palm Sunday | Multiple [Show] | Multiple Types |
| Sun, April 5 | Cheng Ming Festival | Macau | Public Holiday |
| Sun, April 5 | A Drop of Water - A grain of Gold | Turkmenistan | Observance |
| Sun, April 5 | Arbor Day | South korea | Observance |
| Sun, April 5 | Daylight Saving Time ends | Namibia | Clock Change/daylight Saving Time |
| Mon, April 6 | International Day of Sport for Development and Peace | - | International |
| Mon, April 6 | National Tartan Day | Multiple [Show] | Observance |
| Mon, April 6 | President Ntaryamira Day | Burundi | Public Holiday |
| Tue, April 7 | United Nations' World Health Day | - | International |
| Tue, April 7 | Day of Remembrance of the Victims of the Rwanda Genocide | - | International |
| Tue, April 7 | Motherhood and Beauty Day | Armenia | Observance |
| Tue, April 7 | Health Day | Mongolia | Observance |
| Tue, April 7 | God of Medicine's Birthday | Taiwan | Observance |
| Tue, April 7 | Mozambican Woman's Day | Mozambique | Public Holiday |
| Tue, April 7 | Karume Day | Tanzania | Public Holiday |
| Tue, April 7 | Tutsi Genocide Memorial Day | Rwanda | Public Holiday |
| Tue, April 7 | National Beer Day | United states | |
| Wed, April 8 | International Romani Day (for Romani community) | Macedonia, republic of | Optional Holiday |
| Wed, April 8 | Day of Romas | Kosovo | Observance |
| Thu, April 9 | Maundy Thursday | Multiple [Show] | Multiple Types |
| Thu, April 9 | First day of Passover | Multiple [Show] | Multiple Types |
| Thu, April 9 | The Day of Valor | Philippines | Regular Holiday |
| Thu, April 9 | Independence Restoration Day | Georgia | Public Holiday |
| Thu, April 9 | Passover (first day) | United states | Jewish Holiday |
| Thu, April 9 | Constitution Day of the Republic of Kosovo | Kosovo | Official Holiday |
| Thu, April 9 | Vimy Ridge Day | Canada | Observance |
| Thu, April 9 | Imam Mahdi's birthday | Iran | National Holiday |
| Thu, April 9 | Pesach I (First day of Passover) | Israel | National Holiday, Hebrew |
| Thu, April 9 | Martyrs' Day | Tunisia | Public Holiday |
| Fri, April 10 | Good Friday | Multiple [Show] | Multiple Types |
| Fri, April 10 | Pesach II (Passover) | Israel | Observance, Hebrew |
| Sat, April 11 | Holy Saturday | Multiple [Show] | Multiple Types |
| Sat, April 11 | Easter Saturday | Multiple [Show] | Multiple Types |
| Sat, April 11 | Battle of Rivas | Costa rica | National Holiday |
| Sat, April 11 | Pesach III (Passover) | Israel | Observance, Hebrew |
| Sat, April 11 | National Pet Day | - | Weird |
| Sun, April 12 | Grilled Cheese Day | - | Weird |
| Sun, April 12 | Catholic Easter Sunday | Belarus | Observance |
| Sun, April 12 | Easter Sunday | Multiple [Show] | Multiple Types |
| Sun, April 12 | Easter Day | Multiple [Show] | Multiple Types |
| Sun, April 12 | International Day of Human Space Flight | - | International |
| Sun, April 12 | Easter | Multiple [Show] | Multiple Types |
| Sun, April 12 | Children´s Day | Bolivia | Observance |
| Sun, April 12 | Pesach IV (Passover) | Israel | Observance, Hebrew |
| Mon, April 13 | Easter Monday | Multiple [Show] | Multiple Types |
| Mon, April 13 | Thomas Jefferson's Birthday | United states | Observance |
| Mon, April 13 | Pesach V (Passover) | Israel | Observance, Hebrew |
| Mon, April 13 | Easter Monday (bank holiday) | Malta | Bank Holiday |
| Mon, April 13 | Unfairly Prosecuted Persons Day | Slovakia | Observance |
| Mon, April 13 | Family Day | South africa | Public Holiday |
| Mon, April 13 | Dyngus day | Multiple [Show] | Observance |
| Tue, April 14 | Easter Tuesday | Australia (Tasmania) | State Holiday |
| Tue, April 14 | National Library Workers' Day | United states | Observance |
| Tue, April 14 | America Day | Honduras | National Holiday |
| Tue, April 14 | Pesach VI (Passover) | Israel | Observance, Hebrew |
| Tue, April 14 | Tamizh Puttaandu | Mauritius | Public Holiday |
| Tue, April 14 | Cake and Cunnilingus Day | - | Weird |
| Wed, April 15 | Tax Day | United states | Observance |
| Wed, April 15 | Father Damien Day | United states (Hawaii) | Local Observance |
| Wed, April 15 | Birth Date of Kim Il Sung | North korea | Public Holiday |
| Wed, April 15 | Pesach VII (Last day of Passover) | Israel | National Holiday, Hebrew |
| Wed, April 15 | Matsu's Birthday | Taiwan | Observance |
| Thu, April 16 | Wear Pajamas to Work Day | - | Weird |
| Thu, April 16 | Last day of Passover | Multiple [Show] | Multiple Types |
| Thu, April 16 | Last Day of Passover | Multiple [Show] | Multiple Types |
| Thu, April 16 | Emancipation Day | United states (District Of Columbia) | State Holiday |
| Thu, April 16 | National High Five Day | - | Weird |
| Fri, April 17 | Good Friday (Orthodox) | Multiple [Show] | Multiple Types |
| Fri, April 17 | Good Friday | Multiple [Show] | Multiple Types |
| Fri, April 17 | Orthodox Good Friday | Multiple [Show] | Multiple Types |
| Fri, April 17 | Coptic Good Friday | Egypt | Observance |
| Fri, April 17 | Ethiopian Good Friday | Ethiopia | Public Holiday |
| Fri, April 17 | Independence Day | Syria | Public Holiday |
| Fri, April 17 | Women's Rights Day | Gabon | Public Holiday |
| Fri, April 17 | Fast and Prayer Day | Liberia | Public Holiday |
| Fri, April 17 | Herbalist Day | - | Weird |
| Sat, April 18 | Birthday of Guru Angad Dev | - | Sikh |
| Sat, April 18 | Holy Saturday (Orthodox) | Cyprus | Observance, Orthodox |
| Sat, April 18 | International Day for Monuments and Sites | - | International |
| |
| Sat, April 18 | Easter Saturday (Orthodox) | Multiple [Show] | Observance, Orthodox |
| Sat, April 18 | Orthodox Holy Saturday | Multiple [Show] | Multiple Types |
| Sat, April 18 | Coptic Holy Saturday | Egypt | Observance |
| Sat, April 18 | Holy Saturday | Bulgaria | National Holiday |
| Sat, April 18 | Independence Day | Zimbabwe | Public Holiday |
| Sun, April 19 | Orthodox Easter Sunday | Multiple [Show] | Multiple Types |
| Sun, April 19 | Orthodox Easter Day | Multiple [Show] | Multiple Types |
| Sun, April 19 | Easter Sunday (Orthodox) | Multiple [Show] | Multiple Types |
| Sun, April 19 | Landing of the 33 orientals | Uruguay | Bank Holiday |
| Sun, April 19 | Easter Sunday | Multiple [Show] | Multiple Types |
| Sun, April 19 | Orthodox Easter | Multiple [Show] | Orthodox |
| Sun, April 19 | Coptic Easter Sunday | Egypt | National Holiday |
| Sun, April 19 | Ethiopian Easter Sunday | Ethiopia | Public Holiday |
| Sun, April 19 | Declaration of Independence | Venezuela | National Holiday |
| Sun, April 19 | Coptic Easter | Sudan | Public Holiday |
| Sun, April 19 | Birthday of King Mswati III | Swaziland | Public Holiday |
| Sun, April 19 | Bicycle Day | - | Weird |
| Mon, April 20 | Orthodox Easter Day holiday | Ukraine | National Holiday, Orthodox |
| Mon, April 20 | Easter Monday (Orthodox) | Multiple [Show] | Multiple Types |
| Mon, April 20 | Chinese Language Day | - | International |
| Mon, April 20 | Easter Monday | Multiple [Show] | Multiple Types |
| Mon, April 20 | Queen's Birthday | Saint helena | Public Holiday |
| Mon, April 20 | Orthodox Easter Monday | Multiple [Show] | Multiple Types |
| Mon, April 20 | Patriot's Day | United states (Maine, Massachusetts) | State Holiday |
| Mon, April 20 | Spring Festival | Egypt | National Holiday |
| Mon, April 20 | St. George's Day | Canada (Newfoundland And Labrador) | Local Holiday |
| Mon, April 20 | Sechseläuten | Switzerland (Zurich) | Observance |
| Mon, April 20 | Lima Bean Respect Day | - | Weird |
| Tue, April 21 | Orthodox Easter Tuesday (banks only) | Cyprus | Bank Holiday |
| Tue, April 21 | Yom HaShoah | Multiple [Show] | Jewish Holiday |
| Tue, April 21 | San Jacinto Day | United states (Texas) | State Holiday |
| Tue, April 21 | Queen's Birthday | Falkland islands | Public Holiday |
| Tue, April 21 | Tiradentes Day | Brazil | National Holiday |
| Tue, April 21 | Yom HaShoah/Holocaust Memorial Day | Israel | Observance, Hebrew |
| Wed, April 22 | Earth Day | - | International |
| Wed, April 22 | Oklahoma Day | United states (Oklahoma) | Local Observance |
| Wed, April 22 | Administrative Professionals Day | United states | Observance |
| Wed, April 22 | Holocaust Remembrance Day | Serbia | Observance |
| Thu, April 23 | St. George's Day | United kingdom | Observance |
| Thu, April 23 | World Book and Copyright Day | - | International |
| Thu, April 23 | English Language Day | - | International |
| Thu, April 23 | National Sovereignty and Children's Day | Turkey | National Holiday |
| Thu, April 23 | Take our Daughters and Sons to Work Day | United states | Observance |
| Thu, April 23 | Day of Turks | Kosovo | Observance |
| Thu, April 23 | Language Day | Colombia | Observance |
| Thu, April 23 | Day of Aragón | Spain (Aragon) | Local Holiday |
| Thu, April 23 | St George's Day | Spain (Catalonia) | Local Holiday |
| Thu, April 23 | Castile and León Day | Spain (Castile-leon) | Local Holiday |
| Thu, April 23 | First Day of Summer | Iceland | National Holiday |
| Thu, April 23 | German Beer Day | Germany | Observance |
| Thu, April 23 | Girls' Day - Career Information Day | Germany | Observance |
| Thu, April 23 | St George's Feast | Holy see (vatican city) | National Holiday |
| Thu, April 23 | Shakespeare Day | United kingdom | Observance |
| Fri, April 24 | Ramadan begins | Multiple [Show] | Multiple Types |
| Fri, April 24 | Action Day for Tolerance and Respect between People | Argentina | Observance |
| Fri, April 24 | Ramadan starts | Multiple [Show] | Multiple Types |
| Fri, April 24 | Genocide Remembrance Day | Armenia | National Holiday |
| Fri, April 24 | Arbor Day | United states (Nebraska) | State Holiday |
| Fri, April 24 | Concord Day | Niger | Public Holiday |
| Sat, April 25 | National Flag Day | Multiple [Show] | Public Holiday |
| Sat, April 25 | ANZAC Day | Multiple [Show] | Multiple Types |
| Sat, April 25 | World Malaria Day | - | International |
| Sat, April 25 | Liberty Day | Portugal | National Holiday |
| Sat, April 25 | Sinai Liberation Day | Egypt | National Holiday |
| Sat, April 25 | Liberation Day | Italy | National Holiday |
| Sat, April 25 | The Feast of St Mark | Italy | Local Holiday |
| Sat, April 25 | Children´s Day | Colombia | Observance |
| Sat, April 25 | Chosun People's Army Foundation Day | North korea | Public Holiday |
| Sun, April 26 | Day of Remembrance of the Chernobyl Tragedy | Belarus | Observance |
| Sun, April 26 | Turkmen Racing Horse Festival | Turkmenistan | Observance |
| Sun, April 26 | World Intellectual Property Day | - | International |
| Sun, April 26 | State Holiday | United states (Florida) | Local Observance |
| Sun, April 26 | Secretaries' Day | Colombia | Observance |
| Sun, April 26 | Intellectual Property Day | Mongolia | Observance |
| Sun, April 26 | Union Day | Tanzania | Public Holiday |
| Mon, April 27 | King's Birthday | Multiple [Show] | Multiple Types |
| Mon, April 27 | King's Day | Multiple [Show] | Public Holiday |
| Mon, April 27 | ANZAC Day | Australia (Australian Capital Territory, Western Australia) | National Holiday |
| Mon, April 27 | Confederate Memorial Day | United states (Alabama, Florida) | State Holiday |
| Mon, April 27 | State Holiday | United states (Georgia) | State Holiday |
| |
| Mon, April 27 | ANZAC Day observed | New zealand | National Holiday |
| Mon, April 27 | Memorial Day/Parents' Day | Moldova | National Holiday |
| Mon, April 27 | State Flag Day | Moldova | Observance |
| Mon, April 27 | Independence Day | Multiple [Show] | Public Holiday |
| Mon, April 27 | Day of Uprising Against Occupation | Slovenia | National Holiday |
| Mon, April 27 | Freedom Day | South africa | Public Holiday |
| Tue, April 28 | National Heroes Day | Barbados | Public Holiday |
| Tue, April 28 | Afghan Victory Day | Afghanistan | Public Holiday |
| Tue, April 28 | World Day for Safety and Health at Work | - | International |
| Tue, April 28 | Workers' Memorial Day | Gibraltar | Public Holiday |
| Tue, April 28 | Yom HaZikaron (Memorial Day) | Israel | Observance, Hebrew |
| Wed, April 29 | Day of Remembrance for all Victims of Chemical Warfare | - | International |
| Wed, April 29 | Yom HaAtzmaut | Multiple [Show] | Jewish Holiday |
| Wed, April 29 | Yom Ha'atzmaut | United states | Jewish Holiday |
| Wed, April 29 | Day of Trees | Colombia | Observance |
| Wed, April 29 | Shōwa Day | Japan | National Holiday |
| Wed, April 29 | Yom HaAtzmaut (Independence Day) | Israel | National Holiday, Hebrew |
| Wed, April 29 | International Dance Day | - | Weird |
| Thu, April 30 | St. James the Great Day | - | Christian |
| Thu, April 30 | Children's Day | Mexico | Observance |
| Thu, April 30 | Carnival Day | Multiple [Show] | Public Holiday |
| Thu, April 30 | Buddha's Birthday | Multiple [Show] | Multiple Types |
| Thu, April 30 | International Jazz Day | - | International |
| Thu, April 30 | Liberation Day/Reunification Day | Vietnam | National Holiday |
| Thu, April 30 | Walpurgis Night | Multiple [Show] | Multiple Types |
| Thu, April 30 | Education Day | Congo democratic republic | Public Holiday |
