Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Machines maintains its standards for the high quality of its published papers. Thanks to the cooperation of our reviewers, in 2020, the median time to first decision was 16 days and the median time to publication was 35.5 days. The editors would like to express their sincere gratitude to the following reviewers for their precious time and dedication, regardless of whether the papers were finally published:
| Aboltinš, Aivars | Leithardt, Valderi |
| Abu-Mahfouz, Issam | Leiviskä, Kauko |
| Achiaga Menor, Beatriz | Lermen, Richard Thomas |
| Adamczuk Oliveira, Gilson | Leturiondo, Urko |
| Ahmadi, S. Farzad | Li, Jinxing |
| Aiello, Orazio | Li, Tao |
| Alatawneh, Natheer | Li, Yang |
| Alexandridis, Antonio T. | Li, Yongbo |
| Amabili, Marco | Liang, Zhiqiang |
| Amafabia, Daerefa-a Mitsheal | Lin, Jia |
| Ambrosio-lazaro, Roberto Carlos | Lisiński, Przemysław |
| Amezquita-Sánchez, Juan Pablo | Lisjak, Dragutin |
| Amirat, Yassine | Liu, Haitao |
| Andreev, Sergey | Liu, Jiechao |
| Andrei, Gabriel | Liu, Quanying |
| Araujo, Jefferson | Liu, Zhen |
| Arias Garcia, Janier | Longstaff, Andrew Peter |
| Arrabal-Campos, Francisco Manuel | Lopac, Nikola |
| Ayaso, Francisco-Javier | Łukaszewicz, Andrzej |
| Bahmani, Hamed | Łukianowicz, Czeslaw |
| Barriobero-Vila, Pere | Lumentut, Mikail |
| Bartkowiak, Tomasz | Lv, Chen |
| Baszynski, Marcin | Maalouf, Azar |
| Bechtsis, Dimitrios | Machado, Tiago Henrique |
| Becker, Marcelo | Magdziak, Marek |
| Beltran-Carbajal, Francisco | Makris, Sotiris |
| Benardos, Panorios | Mandolini, Marco |
| Benbouzid, Mohamed | Marin, Luis |
| Binkowski, Tomasz | Marsavina, Liviu |
| Bondarev, Andrey V. | Martino, José Mario De |
| Borchers, Christine | Martino, Luca |
| Boscariol, Paolo | Mateev, Valentin |
| Breaz, Radu-Eugen | Mattiazzo, Giuliana |
| Breitbarth, Eric | MEDVEĎ, Dušan |
| Brumerčík, František | Mendes, Ricardo Ugliara |
| Bucci, Giorgia | Meng, Yu |
| Bulgariu, Laura | Mercader, Pedro |
| Bützer, Tobias | Mercorelli, Paolo |
| Cabboi, Alessandro | Mikó, Balázs |
| Capata, Roberto | Mikolajczyk, Tadeusz |
| Castelli-Dezza, Francesco | Miller, Boris |
| Catalin Daniel, Galatanu | Minussi, Carlos Roberto |
| Cavalaris, Chris | Mirvakili, Seyed M. |
| Cavas-Martínez, Francisco | Mo, Jiliang |
| Cechowicz, Radoslaw | Molnár, Viktor |
| Ceruti, Alessandro | Montes, Hector |
| Chatterton, Steven | Moore, Philip |
| Chávez, Esteban | Motzki, Paul |
| Chen, Syuan-Yi | Muscato, Giovanni |
| Cheng, Guangxu | Nagel, Jürgen |
| Cho, Dang-il | Nahata, Sudhanshu |
| Chronopoulos, Dimitrios | Newcomb, Robert |
| Chudzikiewicz, Andrzej | Nguyen, Binh P. |
| Cicconi, Paolo | Nieuwenhuisen, Matthias |
| Cicero, Sergio | Nikolov, Ivan Adriyanov |
| Cirlugea, Mihaela | Offner, Günter |
| Cocuzza, Silvio | Okumura, Susumu |
| Čorović, Selma | Orosz, Tamás |
| Cosco, Francesco | Orozco, Ulises |
| Cuan-Urquizo, Enrique | Otis, Martin |
| Czerwinski, Frank | Ovseník, Ľuboš |
| Da Costa Neves, Carlos Guilherme | Ozer, Ekin |
| Da Silva, Francisco José Gomes | Pagano, Stefano |
| Dalla Vedova, Matteo D. L. | Palmieri, Marco |
| David, Sergio | Parra, Vicente |
| De Agostinis, Massimiliano | Pasinszki, Tibor |
| De Simone, Marco Claudio | Pastor, Maria Magdalena |
| Deja, Mariusz | Pellegrini, Nicola |
| Di Martino, Ferdinando | Pello, Jimbert |
| Díez-Jiménez, Efrén | Perez-Ramirez, Carlos |
| Dindorf, Ryszard | Peter, Ildiko |
| Ding, Songlin | Pietro, Salvini |
| Djukic, Milos B. | Piłat, Adam |
| Dmitrievskii, Vladimir | PILAT, Adam Krzysztof |
| D’Orazio, Antonella | Pinho, Tatiana M. |
| Duan, Molong | Placzek, Marek |
| Dyl, Tomasz | Poboroniuc, Marian |
| Dzwonkowski, Ariel | Popa, Dan Cristian |
| Eliseev, Sergey | Puertas, Ignacio |
| Elosegui, Ibon | Pujol Vazquez, Gisela |
| Fargnoli, Mario | Qin, Zhaoye |
| Farlik, Jan | Qiu, Mingbo |
| Fernandes Rodrigues, Maria Helena | Qiu, Zhicheng |
| Fernández, Julio Blanco | Qu, Haibo |
| Fernandez-Vidal, Severo Raul | Quaglia, Giuseppe |
| Filip, Petr | Ramakrishnan, Ambur |
| Foglia, Giovanni Maria | Rascon, Caleb |
| Fortuna, Luigi | Rassõlkin, Anton |
| Főző, Ladislav | Rauh, Andreas |
| França, Thiago Valle | Raush, Gustavo |
| Francesconi, Marco | Riba Ruiz, Jordi-Roger |
| Friedman, Keith | Rodríguez-Licea, Martín-A. |
| Frizziero, Leonardo | Rodriguez-Resendiz, Juvenal |
| Fu, Chao | Romano, Donato |
| Fydrych, Dariusz | Romano, Elio |
| Galante, Francesco | Rowe, Brian |
| Galdos, Lander | Rozumek, Dariusz |
| Gao, Wei | Sakib, Ashiq |
| García Diez, Ana | Salmi, Mika |
| Garcia, Angel Pontin | Sarfraz, Shoaib |
| García-Berná, José Alberto | Sasaki, Ken |
| Gasiyarov, Vadim | Sauer, Hans Martin |
| Gasparetto, Alessandro | Schiopu, Ionut |
| Gasteratos, Antonios | Schoop, Julius |
| Gavalas, Evangelos | Sedikki, Lynda |
| Ge, Dongdong | Semaltianos, Nikolaos G. |
| Gere, Attila | Shadloo, Mostafa Safdari |
| Gherman, Bogdan | Shamsuzzoha, A.H.M. |
| Giasin, Khaled | Shan, Sicong |
| Giberti, Hermes | Shanbhag, Vignesh |
| Gierz, Lukasz | Shaw, Alexander |
| Giorgio, Ivan | Shen, Yang |
| Giudice, Fabio | Shevtsov, Sergey N. |
| Gligor, Adrian | Shu, Liang |
| Glowacz, Adam | Siami, Ali |
| Gnaciński, Piotr | Sikström, Fredrik |
| Godoy, Antonio José Calderón | Silva, Cristóvão |
| Gonzalez, Fernando | Sinha, Jyoti |
| González, Hernán | Skidanov, Roman |
| Górnicki, Krzysztof | Skoczypiec, Sebastian |
| Graba, Marcin | Slatineanu, Laurentiu |
| Grasso, Marzio | Slavov, Stoyan |
| Gu, Yingkui | Sobótka, Maciej |
| Guerra Rosa, Luis | Socha, Grzegorz |
| Guida, Domenico | Starman, Bojan |
| Guo, Bingyong | Štumberger, Gorazd |
| Guo, Jiang | Su, Hang |
| Haddad, Malik | Sultan, Ibrahim |
| Hajžman, Michal | Sun, Daniel(Jian) |
| Hameed, Saqib | Sun, Fuming |
| Han, Yiwei | Sun, Xiuxuan |
| Harik, El Houssein Chouaib | Szabo, Lorand |
| Hasegawa, Makoto | Szcześniak, Paweł |
| Hassanin, Hany | Szybiński, Bogdan |
| Hatada, Ruriko | Taylor, Matthew E. |
| Haupt, Michael | Tekes, Ayse |
| Hegab, Hussien | Teso-Fz-Betoño, Daniel |
| Heinemann, Robert | Tkach, Itshak |
| Herdzik, Jerzy | Tomporowski, Andrzej |
| Hlaváč, Libor M. | Tong, Zhizhong |
| Hocko, Marian | Tsiligkaridis, John (Ioannis) |
| Hong, Zhonghua | Tysiac, Pawel |
| Hoyos Velasco, Fredy | Uccheddu, Francesca |
| Hsu, Hsien-Pin | Vaimann, Toomas |
| Hu, Zhongwei | Valencia-Palomo, Guillermo |
| Hussain, Ghulam | Valtierra-Rodriguez, Martin |
| Huzlik, Rostislav | Vasilescu, Mircea Dorin |
| Hwangbo, Hyunwoo | Vázquez, Javier |
| Ibrahim, Mohamed Nabil Fathy | Vekinis, George |
| Illana, Irene Del Sol | Vereshchaka, Alexey A. |
| Jafari, Raheleh | Verotti, Matteo |
| Jalil, Bushra | Vidoni, Renato |
| Jarzebowicz, Leszek | Viola, Fabio |
| Jasińska, Elżbieta | Virag, Zoltan |
| Javorski Eckert, Jony | Virgala, Ivan |
| Jeng, Jeng-Ywan | Vonásek, Vojtěch |
| Jerman, Andrej | Wagner, Bernardo |
| Ji, Ai-hong | Wang, Liming |
| Józefczak, Arkadiusz | Wang, Qian Janice |
| Ju, Feng | Wang, Shuangyi |
| Kalinichenko, Antonina | Wei, Zhouchao |
| Kamamichi, Norihiro | Wiens, Travis |
| Kamel, Mohamed A. | Willert, Andreas |
| Kamenar, Ervin | Wiora, Józef |
| Kapcia, Konrad Jerzy | Woizeschke, Peer |
| Kavadias, Kosmas | Wojciechowski, Szymon |
| Kechagias, John D. | Wu, Huachun |
| Kim, Jaemin | Wu, Molei |
| Kim, Wonhee | Xia, Tangbin |
| Klimenda, František | Xiang, Jiawei |
| Koelmel, Bernhard | Xin, Guiyang |
| Kondratiuk, Mirosław | Xu, Kele |
| Korlos, Apostolos | Xu, Xiaowen |
| Kostrzewski, Mariusz | Xue, Jinlin |
| Kostyła, Paweł | Yan, Yu |
| Kounalakis, Tsampikos | Yang, Zebin |
| Koutsovasilis, Panagiotis | Yellavajjala, Ravi Kiran |
| Kowalik, Rafał | Yin, Tao |
| Krah, Jens Onno | Yoder, Aaron |
| Krzeszowski, Tomasz | Zahedi, Abolfazl |
| Kuczmaszewski, Jozef | Zampieri, Nicolò |
| Kulisz, Monika | Zeljkovic, Milan |
| Kuok, Sin-Chi | Zhang, Heye |
| Kuruc, Marcel | Zhang, Hong |
| Kyratsis, Panagiotis | Zhang, Lei |
| Lambán, María Pilar | Zhang, Shenli |
| Lang, Lihui | Zhang, Xuewei |
| Lastra, Jose Martinez | Zhang, Yan |
| Lazarescu, Lucian | Zhao, Jiwen |
| Lazarou, Stavros | Zhou, Ying-Guo |
| Lee, Chul-Hee | Zhukov, Aleksei |
| Lee, Gee-Soo | Zidek, Kamil |
| Lehikoinen, Antti | Żołek-Tryznowska, Zuzanna |
| Leirós-Rodríguez, Raquel | Zou, Ting |
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