The series primarily tells the story of Charlie Spring (Joe Locke), a gay schoolboy who falls in love with classmate Nick Nelson (Kit Connor), whom he sits next to in his new form.

It also explores the lives of their friends Tao Xu (William Gao), Elle Argent (Yasmin Finney), Isaac Henderson (Tobie Donovan), Tara Jones (Corinna Brown) and Darcy Olsson (Kizzy Edgell).

The cinematography and colour grading were planned ahead to give the series a unique atmosphere, amplified by the use of traditional animation adapted from the source material.

[10] Netflix "Kids & Family Content" director Alexi Wheeler said that the story "deserves to be told" due to its relatability among the young demographic.

[14] Oseman explained that the character Aled Last would not appear in the adaptation to respect his story in another novel within the Heartstopper universe, Radio Silence.

After over 10,000 people auditioned via Zoom, she announced the first round of casting decisions in April 2021, with Kit Connor and Joe Locke starring as Nick and Charlie respectively.

[16] After agreeing that Locke suited Charlie's role, Connor was auditioned and the production team found chemistry between the two;[10] the actors themselves recalled only taking a few hours to bond.

[16] The rest of the cast members were announced days later and included Yasmin Finney, Sebastian Croft, William Gao, Corinna Brown, Kizzy Edgell, Cormac Hyde-Corrin, Rhea Norwood and Tobie Donovan.

[10] In July 2022, an open casting call was announced for a 16-year-old character named Sahar Zahid, a British female or non-binary person of South Asian descent.

Other roles announced included Jack Barton as David, Nick's older brother; Bradley Riches as Truham student James McEwan; and Nima Taleghani as schoolteacher Mr Farouk.

[21][22] In November 2022, it was announced that Colman, Chetna Pandya, Fisayo Akinade and Alan Turkington would reprise their roles in the second season, along with new casting including Bel Priestley and Ash Self as Elle's new friends Naomi and Felix respectively, with Thibault de Montalembert as Nick's father Stéphane.

[32] In the episode "Boyfriend", during a scene where Nick and Charlie take a train, Oseman decided to give herself a cameo as a passenger; she is drawing the couple nearby.

Using two Arri Alexa Mini LFs with Canon K35 spherical lenses, she used hand-held cinematography to give the cast space and to achieve an effect that resembled the documentary genre.

With production designer Tim Dickel, they conceived a light-hearted colour palette of orange, yellow, turquoise and a mix of pink and blue.

[10] As Tara and Darcy kiss in the third episode, Nick is bathed in bisexual lighting (pinks, purples and blues) symbolising him realising his sexuality; this was suggested to Olifirova by the series' creative team.

[36] Production designer Tim Dickel worked with set decorator Maxwell Fine, who used his experience in past art lessons to create a realistic representation of British classrooms.

[41] A sequence set in the Eiffel Tower was filmed in "two mornings"; the cast and crew needed to reach there by 06:00 local time prior to being open for public.

Other locations include the Shakespeare and Company bookstore; the Arc de Triomphe; the Pont des Arts; a café by the Seine; and the Marais, known as a centre of LGBT culture.

Costume designer Adam Dee wanted the series to feature more casual clothing and made T-shirts for Nick and Charlie that resembled the cover of the novel's third volume.

[40] Tao's new haircut was inspired by Chow Mo-wan, the male main character of one of his favourite films, In the Mood for Love (2000), whose poster is also featured in his bedroom.

She had already thought of using such effects while writing the screenplay, conceiving that they would appear primarily during the intimate scenes between Nick and Charlie, which she dubbed "Heartstopper moments".

Hilary Remley, who wrote the news, saw the teaser as teasing the series's "emotionally vulnerable" air, "showing the experience of teenage love in a direct and sincere way", assured that audiences will enjoy the final product due to its faithfulness to the source material's dreamlike aesthetic.

[70][71] All music is composed by Adiescar Chase, except where notedDuring its debut week, Heartstopper ranked at number seven on Netflix's Top ten TV British titles just two days after its release.

[78] The show appeared in the Top 10 list in three countries where same-sex relations are illegal[79] (Lebanon,[80] Saudi Arabia,[81] and Sri Lanka).

The website's critical consensus reads: "An inclusive romance told with striking sensitivity, Heartstopper is so effortlessly charming that viewers won't dare skip a beat.

[88] Reviewing the series for The Guardian, Rebecca Nicholson gave a rating of four out of five, and said, "Heartstopper may not quite live up to the dramatic promise of its title, but this adorable teen romance is a heartwarmer, at the very least.

Club gave the series an A− and said "Thankfully, Heartstopper subverts notions by keeping its protagonist proudly gay: It's the love interest who has to sort through his unexpected feelings, not the other way around.

"[90] Digital Spy's David Opie gave a rating of 5/5 and said, "Heartstopper centres queer love, affirming the feelings of young people watching who might be unsure or afraid to speak their truth.

"[91] Jonathan Wilson of Ready Steady Cut gave a rating of four out of five and stated, "Heartstopper might lack some edge and feel as if it's speaking to a younger demographic than the usual teen drama, but its deeply uplifting portrait of young love is very difficult not to get swept up in.

Songs on the soundtrack that received a surge in chart sales when compared to the previous week included "Want Me" and "Dover Beach" by Baby Queen, "Why Am I Like This?"