9 Best Sci-Fi Books to Read Free Online
Science fiction is the genre of what if. What if humanity made first contact with aliens who cared more about our food than our technology? What if a time portal in your pantry took you back to 1995? What if a video game entity started punishing real-world criminals? Every sci-fi novel starts with a question that can't be asked in any other genre, and the best ones answer it in ways that change how you see the present, not just the future.
This is a list of 9 free sci-fi books you can read right now on NovelDay, all in the Sci-Fi genre, ranging from a 3.5-hour VR mystery to a 14-hour multi-POV epic. No paywalls, no premium tiers, no "wait 23 hours for the next chapter" timers. Just free fiction, updated regularly by independent authors.
If you've read my horror books guide or my vampire books guide, this list covers different territory. Sci-fi is the second-broadest genre on NovelDay with 17 novels, spanning space opera, military fiction, alien contact, time travel, VR, and post-apocalyptic survival.
What Makes Science Fiction Worth Reading?
Sci-fi works differently from other genres. A romance novel asks whether two people will end up together. A mystery asks who did it. A thriller asks whether the hero will survive. Science fiction asks something bigger: what kind of world do we want to live in, and what happens when we build it?
The genre splits into several subgenres, and the novels on this list span most of them. Here's a quick guide so you can find the type that matches what you're looking for:
Hard sci-fi: The science matters. The story is built around real or plausible technology, physics, or biology. The appeal is watching a logical system play out to its consequences. Think Andy Weir's The Martian or Arthur C. Clarke's Rendezvous with Rama.
Space opera: Big scale, big stakes, big cast. Interstellar empires, space battles, political intrigue across multiple planets. The science is secondary to the adventure. Think Star Wars, Dune, or James S.A. Corey's The Expanse.
Military sci-fi: War stories set in the future. Training academies, battlefronts, chain of command, tactical decisions. The sci-fi elements are weapons, armor, and enemies, but the structure is military fiction. Think Robert Heinlein's Starship Troopers or Joe Abercrombie's Half a King with spaceships.
Alien contact: First encounter stories. What happens when humanity meets an intelligence that isn't human? The best entries in this subgenre use aliens as a mirror to examine human nature. Think Arrival, Ender's Game, or Octavia Butler's Lilith's Brood.
Cyberpunk and VR: Virtual reality, artificial intelligence, corporations replacing governments, the line between human and machine dissolving. Think Neuromancer, Snow Crash, or Ready Player One.
Time travel: The oldest sci-fi device still in active use. The appeal is the paradox: if you change the past, do you erase the present? The best time travel stories use the mechanism to explore regret, memory, and the question of whether anything is inevitable. Think The Time Machine, Slaughterhouse-Five, or Dark.
Most of the novels below blend two or three of these. Pure subgenre entries are rare in web fiction because the serialized format rewards authors who can mix modes and keep multiple threads running. The list below reflects that variety.
9 Best Sci-Fi Books to Read Free Online
The novels below are ordered by reading time, longest first. This puts the most substantial, developed binges at the top. As you scroll down, the time commitment drops. The first three are 10+ hour reads for a full weekend. The last two are under 4 hours for a quick taste. All nine are ongoing and updated regularly by their authors, so even the shorter ones will keep growing.
Every novel is free to read on NovelDay with no paywalls. Click any title to start reading immediately.
1. The Shattering Point
They woke up scattered outside their small hometown with paradoxical memories they can't hold onto. For more than two years, they have fought to get back, but they could never have anticipated what awaits them. A cataclysmic collision with an impossible realm changes Earth forever. But there are others. It is the same event, splintering and conflating reality. One devastating impact across time and space. It is unsustainable. It has reached the shattering point. What if all the stories are true? What if they're all the same story?
This is the longest sci-fi novel on the list and the most ambitious. The author describes it as a multi-POV, multi-genre narrative, which means you're not following one protagonist through one storyline. You're following several characters whose perspectives overlap, contradict, and eventually converge. The #7 weekly ranking with 263 views confirms it's finding an audience. The premise, a single event that fractures reality across time and space, is the kind of high-concept hook that sci-fi does better than any other genre.
If you've read Dark or Stranger Things and wanted something with the same reality-bending ambition but in written form, this is the closest match on NovelDay. 46 chapters and 14 hours of reading time makes it the deepest binge on the list. The multi-POV structure means the pacing stays varied, which helps sustain a long read.
2. The Eyes Series (Books 1 and 2)
Desmond Little, or Dez as he prefers, is a young man from the small town of Eyeville who has never felt at home there. He's been missing something his entire life, and he follows along on an impulsive plan of his best friend, Hooks. This illegal plan leads both of them into dire trouble, which gets worse when they're mixed into a strange conspiracy pertaining to Death Row inmates. As Dez and eleven other prisoners are brought to a new home, their chance at survival depends on uncovering the truth.
This is a two-book series, and I'm featuring it as one entry because the story continues directly from Book 1 to Book 2. What We See: An Eyes Story (Book One) is 4hr 50min with 29 chapters. What We Are: An Eyes Story (Book Two) is 6hr 15min with 37 chapters. Together, that's 11 hours and 66 chapters, the second-deepest binge on this list.
The series blends sci-fi conspiracy with thriller pacing. The Death Row inmate angle gives it a darker edge than most entries on this list, and the small-town setting keeps the early chapters grounded before the scope expands. 227 combined views and a #26-36 weekly ranking suggest a steady readership. If you like your sci-fi with conspiracy thriller elements and a cast of characters who are all hiding something, this is the series on the list that does that best.
3. The 90's Kid
One morning, Wes walked through a mysterious time portal in his pantry door and found himself back in 1995. He was ten years old. The hours were long, childhood stretched to the horizon, and all he needed were his buddies, video games, and TV. Now he's an adult seeing his own childhood from the outside, poking around for secrets he missed, finding out what the adults were up to while he wasn't looking.
This is the time travel entry on the list, but the sci-fi element is quiet. The time portal exists, but the story is about what Wes finds on the other side: a specific childhood in a specific decade, seen with adult eyes. The sci-fi is the mechanism, not the point. What makes it work is the specificity. 1995 isn't a generic past. It's a particular year with particular video games, particular TV shows, and a particular feeling of being ten that anyone who grew up in that era will recognize immediately.
The time travel element puts this novel in the sci-fi category, but the story is really about what Wes finds on the other side: a specific childhood in a specific decade, seen with adult eyes. At 10 hours with 30 chapters, it's one of the longest reads on the list. If you wanted About Time without the romance, just the going-back part, this is the closest thing on NovelDay.
4. Rise of a Champion
Fifteen-year-old orphan Lucille Domitian is meat for the machine. In the brutal Praevecti Academy, she bleeds through six years of savage training, rival knives at her back, and instructors who'd rather bury her than break her. Only her bond with Cain Aurellius keeps her human. The system doesn't just test her. It tries to erase her. She survives anyway.
This is the military sci-fi entry on the list. The Praevecti Academy is a training ground that turns children into weapons, and Lucille's story is about surviving a system designed to destroy her. The 59 chapters in 7 hours mean the pacing is fast, with short chapters that keep the tension high. The bond with Cain Aurellius gives the story a human anchor that prevents it from becoming purely about the training violence.
The #100 weekly ranking with 58 views is modest, but the novel has 59 chapters of content, which means the author has been writing consistently. If you like Ender's Game, Red Rising, or any military academy story where the protagonist has to outfight and outthink everyone who wants them dead, this is the entry on the list that delivers that.
5. The Spartan of Invicta
The Empire of Invicta does not run on mercy. It runs on Houses, Board-chambers, forged gods in warplate, and the living weapons called Vardengard, engineered killers bound by code, collar, and creed. At the empire's exposed center stands Spartan: not a mascot, not a pet legend, but a remote war-architecture in a woman's shape. Whoever holds her holds more than a sword. Whoever fails her holds a throne made of glass.
This is the second novel by Lieutenant 257 on this list, and it's a different subgenre from Rise of a Champion. Where that novel is military academy fiction, this is space opera with political intrigue. The Empire of Invicta is a fully built civilization with its own power structures, and Spartan is a weapon with agency, which is the kind of character concept that sci-fi can explore better than any other genre. 81 chapters in 7 hours means the chapters are very short, which keeps the political maneuvering moving at a brisk pace.
If you like Dune, Warhammer 40K, or any story where empires are held together by weapons that might turn on their wielders, this is the entry on the list that does that. The 72 views and #90 weekly ranking are modest, but 81 chapters of content is substantial.
6. Rosetta's Last Stand
The year is 2051, and Earth is locked in a catastrophic global war. The future seems bleak until a league of food-obsessed aliens show up offering to save humanity from itself, for a price. Turns out it's not the technology, culture, or people who make Earth special. It's the food. And the Kithari are willing to do just about anything to preserve the unique flavors of their new favorite planet. 34 years later, Rose, a produce clerk who loves to cook, receives a phone call that shatters her quiet life.
This is the alien contact entry on the list, and it's the most original premise on NovelDay. Most alien contact stories are about war, diplomacy, or invasion. This one is about food. The Kithari aren't here to conquer. They're here because Earth's cuisine is unique in the galaxy, and they'll protect humanity to keep it. That premise gives the story both humor and stakes, and the 34-year time jump between the alien arrival and Rose's story means the world has already been transformed by the time we enter it.
299 views and a #25 weekly ranking make this the highest-viewed sci-fi novel on the list. The blend of alien contact with culinary focus and a working-class protagonist is the kind of premise that makes sci-fi worth reading: it asks a question no one else has asked, and the answer is surprising. If you liked The Hitchhiker's Guide to the Galaxy but wanted something more grounded, this is the entry on the list that comes closest.
7. Azela Incarnate
Catherine was raised to be a priestess, but on the day of her ordination, she was exiled from the only home she ever knew. With nothing left to lose, she steals what may be the most profane and cursed item in the universe and sets out on a journey. By chance, she witnesses a woman being saved from a magical attack. This woman, Azela, finds herself in a bizarre world she knows nothing about. Their journeys intertwine and evolve into an odyssey of wonders, horrors, and mystery as they seek to uncover the truth.
This is the sci-fi/fantasy hybrid entry on the list. It's tagged Sci-Fi but reads like fantasy with sci-fi elements, which is a common blend in web fiction. The priestess protagonist and the cursed artifact give it a fantasy feel, while the world-hopping and the mysterious woman who doesn't belong suggest a sci-fi framework underneath. The #15 weekly ranking with 265 views makes it one of the highest-ranked novels on this list.
If you like The Wheel of Time but wanted something with sci-fi undertones, or if you like Stargate but wanted more character focus, this is the entry on the list that straddles both genres. 39 chapters in 6 hours means the pacing is steady, with enough room for worldbuilding between the action.
8. Aurea Juniper: A Pokemon Fanfiction
Aurea Juniper is supposed to become her father's perfect assistant: brilliant, obedient, and trapped forever in the cold machinery of Juniper Labs. Jauna is the wild daughter of Nacrene's museum, desperate to prove she is more than her mother's shadow. Hilda wants to become a legend because being forgotten has always felt too much like dying. Aurea wants to keep them together. And the only thing that can lies just beyond her reach.
This is the fanfiction entry on the list, and it's here because the Pokemon universe is fundamentally a sci-fi setting: genetic engineering, artificial creatures, laboratory research, and technology that blurs the line between biology and machinery. The story uses the Pokemon world as a backdrop for a character-driven story about three young women with different ambitions and different fears. The sci-fi elements are the setting. The story is about friendship, ambition, and the gap between who you're supposed to be and who you want to be.
120 views and a #70 weekly ranking with 21 chapters suggest it's finding a niche audience. At 4 hours, it's a shorter read. If you like Pokemon and want a story that takes the worldbuilding seriously without being a retread of the games, this is the most specific entry on the list.
9. Digital Breaths [Book 1]: The Warden of the Grand Prison
![Digital Breaths [Act 1]: The Warden of the Grand Prison](https://novelday.net/api/novels/14754/image/1784375888)
25 years ago, one of the biggest internet mysteries began from one of the most popular games of the 2000s: Lethe. A game that defined the Western RPG genre, and also produced an entity displaying anomalous properties. This being is known as the Warden, a Lethe guard who has been known to aid those in dire need in the real world, and punish those who have committed severe transgressions. The latter disappear under unknown circumstances without a trace. And these disappearances have only sparked more mysteries.
This is the cyberpunk/VR entry on the list, and the premise is the most directly relevant to current anxieties about AI and virtual reality. An entity from a video game that reaches into the real world to punish criminals is the kind of sci-fi concept that works because it's close enough to reality to feel plausible. The 24 chapters in 3.5 hours mean the pacing is tight, and the mystery structure gives each chapter a reason to keep reading.
173 views and a #60 weekly ranking with 24 chapters suggest steady growth. At 3.5 hours, it's the shortest read on the list, but the mystery premise means every chapter matters. If you like Ready Player One but wanted something darker, or if you like The Matrix but wanted a mystery instead of an action story, this is the entry on the list that comes closest.
Where to Read More Sci-Fi Fiction
The 9 novels above are selected from 17 novels in the Sci-Fi genre on NovelDay. 7 were excluded for being under 2 hours of reading time, which is not enough content for a sci-fi story to develop its world and conflict. The Eyes series was grouped from two books into one entry. New novels are added regularly as authors join the platform, so the genre page will have more over time.
If you want to explore more fiction on NovelDay, browse the full catalog at Browse or check specific genres. Sci-fi overlaps with several categories. You'll find it in Adventure, Action, Supernatural, and Horror alike.
For related reading guides:
- 7 Best Horror Books to Read Free Online — horror web novels for when sci-fi isn't dark enough
- 5 Best Vampire Books to Read Free Online — supernatural web novels with crossover appeal
- What is LitRPG? A Complete Guide with Free Web Novels — Digital Breaths has LitRPG elements
- What is Progression Fantasy? A Complete Guide with Free Web Novels — many sci-fi web novels use progression mechanics
Every novel on NovelDay is free to read. No paywalls, no premium tiers, no "wait or pay" timers. Authors post chapters on their own schedules, and you can follow novels to get notified when new chapters drop. If you're a writer with a sci-fi story of your own, you can publish it on NovelDay for free and keep all rights to your work.
