This is a rough scale to measure relative levels of technology. It's based on the one described in the GURPS system created by Steve Jackson Games, with some modifications specific to the Outsider universe.

Tech Level | General Earth Historical Comparison
0 | Stone Age (prior to 3000 BCE): stone tools, pottery, archery, fire, lever, language, animal husbandry, calendar
1 | Bronze Age (3000-600 BCE): copper and bronze working, wheel, writing, agriculture, masonry, sailing, currency
2 | Iron Age (601 BCE-600 CE): iron working, mathematics, keystone arch, concrete, siege engines
3 | Medieval (601-1450): steel tools, optics (telescope), chemistry
4 | Renaissance/Colonial (1450-1800): gunpowder, printing, global navigation, accurate timekeeping
5 | Industrial Revolution (1801-1900): mass production, steam power, railroad, rifling, electricity, telegraph, photography
6 | World Wars (1901-1950): combustion engine, automobiles, airplanes, rockets, radio, radar, atomic weapons
7 | Information Age (1951-2000): television, jet engine, satellites, guided missiles, nuclear energy, computers, lasers, helicopters
8 | Spacefaring (2001-2100): stealth, ion drive, interplanetary travel, fusion power, cybernetics, railguns, bioengineering, 3D printing
9 | Starfaring: (2100-2150): jump drive, interstellar travel, inertial dampers, artificial gravity, antigrav, longevity, shipstones
10 | Antimatter: (2151-?): taimat power, blasters, electromagnetic screens, floater drive
11 | Force: plasma focus, plastron field, wave-loom device, force screens, tractor beams
12 | Spacetime Mastery: reactionless drive, ansible, hyperspace metrics. virtual consciousness
13 | Worldbuilding: jetpacks, personal force screens, unrestricted manipulation of planetary environment
14 | Dysonian: smart materials, replicators, construction of planets, dyson spheres, ringworlds and so on
15 | Superscience: matter transmission, black hole generators
16+ | A Sufficiently Advanced Technology: as you wish...

How do the various races in Outsider rank on this scale?

Humanity is TL9, at the cusp of TL10, having just developed blasters. The Loroi and Umiak (and most of the major combatants) are in the early stages of TL11. The true extent of Historian technology is not known, but is estimated by the Loroi to be somewhere in TL12.