I've gotten half the Guilds written up, so giving a little spoiler.
Society of the Blade: Professional melee fighters, proficient in every weapon they can get their hands on. Dueling to the death is illegal, but they have dozens of ways to duel including first blood, disarm, to the pain, to first to yield or even trying to get their opponent to spill their drink. Often used as bodyguards.
Grimguard: Watchmen that patrol the city. Known for their use of divination magic and enchanted armor that make everyone look like the same person making them impossible to bribe.
Order of the Line: Knightly order focusing on preparing the body and mind for a fight. The most numerous of all the knights in the city.
Protectorate: Knightly order known for its custom crafted magic arms and armor. Charged by the city to help those in need.
Zhakkaz: The army proper, means "Witch Men" in the language of their worst enemy. Fights as one and can manipulate both the elements and the environment.
Order of Thunder: Knightly order comprised of heavy cavalry. Using conjured elemental creatures for mounts, few in number but one of the most lethal fighting forces in the realm.
Free Range Acquisitions League: Privateers that serve as a proxy fighting force against the various empires with eyes on the city.
Aspis: Professional bodyguards that work for the rich and influential, also serve as watchmen for hire for merchants.
Sires of Azarkarde: The idle rich who show off their wealth with bizarre displays of magic and wasteful spending.
Rose and Blade: The Bard's guild, combination of storytellers and musicians. Rivals to the other artists but well liked by the rest.
League of Twelve: Historical nobility from the founding of the city. Not as powerful as they used to be, but with old money and connections still a force to be reckoned with.
Transmorphic Guild: Shapeshifters that try to get others to embrace their ability to use magic to throw off the bounds of their forms.
Grand Bazaar Member's Association: The merchants guild, always trying to monopolize trade in the city and keep trade routes open.
Seekers of the Ill: The plague catchers, medicine men charged to find people harboring illness and quarantine them from the rest of the population.
School of Thaumaturgy: The grand college, though covers all topics not just magic. Comprised of instructors from dozens of schools, they keep the city the best educated on the continent.
Odist's Collective: Poet's guild, known for their mercurial natures. Poorest of the artistic guilds, though in demand in the richer guilds.
Grand Library of Azarkarde: Building the size of several city blocks and even larger on the inside. Contains more knowledge than most nations can claim.
Fellowship of the Serpent: Doctor's guild, running the three largest hospitals. Very traditional and professional, but often overwhelmed by the number of patients.
Society for the Recently Deceased: Necromancer's Guild, takes care of body disposal. With no stigma on necromancy, tries to keep a positive spin on their role.
Foundation for a Better Azarkarde: The bureaucrat's guild, handles the day to day running of the city. Not well liked but needed.
Guild of Information Providers: Couriers that run messages and packages across the city. Known for their ability to run along walls and defy gravity to get their jobs done.
Church of the Holy Crossroad: The Grand Cathedral, maintains shrines to all the Exemplars. Also heavily involved in charities and dealing with tourists.
Eternal Carnival: An always open carnival that spans several blocks of the city. Overpriced, but always full with children and tourists.
Horizon Seekers: The explorers, rarely in the city they travel the known worlds and other planes of existence.
Guild of Negotiable Affections: Courtesans and ladies of the night, present throughout the city but return to their guild for safety.
Sisters of the Golden Note: Guild of healers that try to help as many as they can for free, badly overwhelmed by patients however. Known for being badly managed.
Keepers of the Accord: Smugglers all, they supply the city with untaxed goods and smuggle out the same. Tolerated because of their heavy anti-slaving activities.
Brotherhood of Wealth Reallocation: The thieves guild, a borderline benevolent society. Obeying a strict set of rules they also act as a sort of charity to the poorer guilds.
Followers of the One True Law: Anarchist's guild split between the libertarian types and the true anarchists. Constantly at war with itself, and the violence often spills over.
Provender's Freehold: Farmers and ranchers, make up the largest guild physically. Very conservative in their politics, extremely wealthy because of their exports.
Deathless: Humorless guild of mages that have greatly extended their lives through magic. Frowned on by the other guilds, but as old as the city itself.