diff --git a/src/SolverAPI.jl b/src/SolverAPI.jl
index 327a5be..fb52b48 100644
--- a/src/SolverAPI.jl
+++ b/src/SolverAPI.jl
@@ -97,13 +97,12 @@ function response(
 
     res["termination_status"] = string(MOI.get(model, MOI.TerminationStatus()))
 
-    options = get(() -> Dict{String,Any}(), json, :options)
-    format = get(options, :print_format, nothing)
+    format = get(json.options, :print_format, nothing)
     if !isnothing(format)
         res["model_string"] = print_model(model, format)
     end
 
-    if Bool(get(options, :print_only, false))
+    if Bool(get(json.options, :print_only, false))
         return res
     end
 
@@ -178,12 +177,23 @@ function solve(fn, json::Request, solver::MOI.AbstractOptimizer)
     errors = validate(json)
     isempty(errors) || return response(; errors)
 
+    # TODO (dba) `SolverAPI.jl` should be decoupled from any solver specific code.
+    solver_info = Dict{Symbol,Any}()
+    if lowercase(get(json.options, :solver, "highs")) == "minizinc"
+        T = Int
+        solver_info[:use_indicator] = false
+    else
+        T = Float64
+        solver_info[:use_indicator] = true
+    end
+
+    model = MOI.instantiate(() -> solver; with_cache_type = T, with_bridge_type = T)
+
     try
-        T, solver_info, model = initialize(json, solver)
-        load!(json, T, solver_info, model)
+        set_options!(model, json.options)
+        load!(model, json, T, solver_info)
         fn(model)
-        options = get(() -> Dict{String,Any}(), json, :options)
-        if !Bool(get(options, :print_only, false))
+        if !Bool(get(json.options, :print_only, false))
             MOI.optimize!(model)
         end
         return response(json, model, solver)
@@ -208,6 +218,8 @@ function solve(fn, json::Request, solver::MOI.AbstractOptimizer)
         else
             rethrow()
         end
+    finally
+        MOI.empty!(model)
     end
 end
 solve(request::Request, solver::MOI.AbstractOptimizer) =
@@ -232,30 +244,30 @@ function print_model(model::MOI.ModelLike, format::String)
     format_lower = lowercase(format)
     if format_lower == "moi" || format_lower == "latex"
         mime = MIME(format_lower == "latex" ? "text/latex" : "text/plain")
-        options = MOI.Utilities._PrintOptions(
+        print_options = MOI.Utilities._PrintOptions(
             mime;
             simplify_coefficients = true,
             print_types = false,
         )
         return sprint() do io
-            return MOI.Utilities._print_model(io, options, model)
+            return MOI.Utilities._print_model(io, print_options, model)
         end
     elseif format_lower == "latex"
         # NOTE: there are options for latex_formulation, e.g. don't print MOI function/set types
         # https://jump.dev/MathOptInterface.jl/dev/submodules/Utilities/reference/#MathOptInterface.Utilities.latex_formulation
         return sprint(print, MOI.Utilities.latex_formulation(model))
     elseif format_lower == "mof"
-        options = (; format = MOI.FileFormats.FORMAT_MOF, print_compact = true)
+        print_options = (; format = MOI.FileFormats.FORMAT_MOF, print_compact = true)
     elseif format_lower == "lp"
-        options = (; format = MOI.FileFormats.FORMAT_LP)
+        print_options = (; format = MOI.FileFormats.FORMAT_LP)
     elseif format_lower == "mps"
-        options = (; format = MOI.FileFormats.FORMAT_MPS)
+        print_options = (; format = MOI.FileFormats.FORMAT_MPS)
     elseif format_lower == "nl"
-        options = (; format = MOI.FileFormats.FORMAT_NL)
+        print_options = (; format = MOI.FileFormats.FORMAT_NL)
     else
         throw(Error(Unsupported, "File type \"$format\" not supported."))
     end
-    dest = MOI.FileFormats.Model(; options...)
+    dest = MOI.FileFormats.Model(; print_options...)
     MOI.copy_to(dest, model)
     return sprint(write, dest)
 end
@@ -265,16 +277,15 @@ function print_model(request::Request; T = Float64)
         throw(CompositeException(errors))
     end
 
-    options = get(() -> Dict{String,Any}(), request, :options)
     # Default to MOI format.
-    format = get(options, :print_format, "MOI")
+    format = get(request.options, :print_format, "MOI")
 
     # TODO cleanup/refactor solver_info logic.
     use_indicator = T == Float64
     solver_info = Dict{Symbol,Any}(:use_indicator => use_indicator)
     model = MOI.Utilities.Model{T}()
 
-    load!(request, T, solver_info, model)
+    load!(model, request, T, solver_info)
     return print_model(model, format)
 end
 print_model(request::Dict) = print_model(JSON3.read(JSON3.write(request)))
@@ -289,7 +300,7 @@ function validate(json::Request)#::Vector{Error}
     valid_shape = true
 
     # Syntax.
-    for k in [:version, :sense, :variables, :constraints, :objectives]
+    for k in [:version, :sense, :variables, :constraints, :objectives, :options]
         if !haskey(json, k)
             valid_shape = false
             _err("Missing required field `$(k)`.")
@@ -307,7 +318,7 @@ function validate(json::Request)#::Vector{Error}
         _err("Invalid version `$(repr(json.version))`. Only `\"0.1\"` is supported.")
     end
 
-    if haskey(json, :options) && !isa(json.options, JSON3.Object)
+    if !isa(json.options, JSON3.Object)
         _err("Invalid `options` field. Must be an object.")
     end
 
@@ -326,20 +337,18 @@ function validate(json::Request)#::Vector{Error}
         _err("Invalid `sense` field. Must be one of `feas`, `min`, or `max`.")
     end
 
-    if haskey(json, :options)
-        for (T, k) in [(String, :print_format), (Number, :time_limit_sec)]
-            if haskey(json.options, k) && !isa(json.options[k], T)
-                _err("Invalid `options.$(k)` field. Must be of type `$(T)`.")
-            end
+    for (T, k) in [(String, :print_format), (Number, :time_limit_sec)]
+        if haskey(json.options, k) && !isa(json.options[k], T)
+            _err("Invalid `options.$(k)` field. Must be of type `$(T)`.")
         end
+    end
 
-        for k in [:silent, :print_only]
-            if haskey(json.options, k)
-                val = json.options[k]
-                # We allow `0` and `1` for convenience.
-                if !isa(val, Bool) && val isa Number && val != 0 && val != 1
-                    _err("Invalid `options.$(k)` field. Must be a boolean.")
-                end
+    for k in [:silent, :print_only]
+        if haskey(json.options, k)
+            val = json.options[k]
+            # We allow `0` and `1` for convenience.
+            if !isa(val, Bool) && val isa Number && val != 0 && val != 1
+                _err("Invalid `options.$(k)` field. Must be a boolean.")
             end
         end
     end
@@ -357,29 +366,16 @@ function validate(json::Request)#::Vector{Error}
     return out
 end
 
-function initialize(json::Request, solver::MOI.AbstractOptimizer)#::Tuple{Type, Dict{Symbol, Any}, MOI.ModelLike}
-    solver_info = Dict{Symbol,Any}()
-
-    # TODO (dba) `SolverAPI.jl` should be decoupled from any solver specific code.
-    options = get(() -> Dict{String,Any}(), json, :options)
-    if lowercase(get(options, :solver, "highs")) == "minizinc"
-        T = Int
-        solver_info[:use_indicator] = false
-    else
-        T = Float64
-        solver_info[:use_indicator] = true
-    end
-
-    model = MOI.instantiate(() -> solver; with_cache_type = T, with_bridge_type = T)
-
+# Set solver options.
+function set_options!(model::MOI.ModelLike, options::JSON3.Object)#::Nothing
     if MOI.supports(model, MOI.TimeLimitSec())
         # Set time limit, defaulting to 5min.
         MOI.set(model, MOI.TimeLimitSec(), Float64(get(options, :time_limit_sec, 300.0)))
     end
 
-    # Set other solver options.
     for (key, val) in options
         if key in [:solver, :print_format, :print_only, :time_limit_sec]
+            # Skip - these are handled elsewhere.
             continue
         elseif key == :silent
             MOI.set(model, MOI.Silent(), Bool(val))
@@ -392,10 +388,10 @@ function initialize(json::Request, solver::MOI.AbstractOptimizer)#::Tuple{Type,
         end
     end
 
-    return (T, solver_info, model)
+    return nothing
 end
 
-function load!(json::Request, T::Type, solver_info::Dict{Symbol,Any}, model::MOI.ModelLike)#::Nothing
+function load!(model::MOI.ModelLike, json::Request, T::Type, solver_info::Dict{Symbol,Any})#::Nothing
     # handle variables
     vars_map = Dict{String,MOI.VariableIndex}()
     vars = MOI.add_variables(model, length(json.variables))
diff --git a/test/all_tests.jl b/test/all_tests.jl
index b9bef13..4bee924 100644
--- a/test/all_tests.jl
+++ b/test/all_tests.jl
@@ -21,7 +21,12 @@ end
 
 function run_solve(input::String)
     json = deserialize(input)
-    solver = get_solver(json.options.solver)
+    solver_name = try
+        json.options.solver
+    catch
+        "highs"
+    end
+    solver = get_solver(solver_name)
     output = solve(json, solver)
     return String(serialize(output))
 end
@@ -34,18 +39,19 @@ end # end of setup module.
 @testitem "print" setup = [SolverSetup] begin
     using SolverAPI: print_model
 
-    model = Dict(
+    json = Dict(
         :version => "0.1",
         :sense => "min",
         :variables => ["x"],
         :constraints => [["==", "x", 1], ["Int", "x"]],
         :objectives => ["x"],
+        :options => Dict(:print_format => "none"),
     )
 
     # check MOI model printing for each format
     @testset "$f" for f in ["moi", "latex", "mof", "lp", "mps", "nl"]
-        request = Dict(model..., :options => Dict(:print_format => f))
-        @test print_model(request) isa String
+        json[:options][:print_format] = f
+        @test print_model(json) isa String
     end
 end
 
@@ -91,6 +97,8 @@ end
         ("missing_sense", "InvalidFormat"),
         # missing field version
         ("missing_version", "InvalidFormat"),
+        # missing field options
+        ("missing_options", "InvalidFormat"),
         # field variables is not a string
         ("vars_is_not_str", "InvalidFormat"),
         # field variables is not an array
@@ -125,6 +133,7 @@ end
         ("unsupported_print_format", "Unsupported"),
     ]
 
+    # check that expected error types are returned for each json input
     @testset "$j" for (j, es...) in json_names_and_errors
         result = JSON3.read(run_solve(read_json("inputs", j)))
         @test haskey(result, :errors) && length(result.errors) >= 1
@@ -138,18 +147,21 @@ end
     # setup linear objective model with n variables
     n = 1000
     vars = ["x$i" for i in 1:n]
-    model = Dict(
+    json = Dict(
         :version => "0.1",
         :sense => "max",
         :variables => vars,
         :constraints => [["Bin", v] for v in vars],
         :objectives => [vcat("+", 1, [["*", i, v] for (i, v) in enumerate(vars)])],
+        :options => Dict(:solver => "HiGHS"),
     )
 
     # check that model is solved correctly without errors
-    output = solve(model, get_solver("HiGHS"))
-    @test output isa Dict{String,Any}
-    @test !haskey(output, "errors")
-    @test output["termination_status"] == "OPTIMAL"
-    @test output["results"][1]["objective_value"] ≈ 1 + div(n * (n + 1), 2)
+    @testset "solve n=$n" begin
+        output = solve(json, get_solver("HiGHS"))
+        @test output isa Dict{String,Any}
+        @test !haskey(output, "errors")
+        @test output["termination_status"] == "OPTIMAL"
+        @test output["results"][1]["objective_value"] ≈ 1 + div(n * (n + 1), 2)
+    end
 end
diff --git a/test/inputs/missing_options.json b/test/inputs/missing_options.json
new file mode 100644
index 0000000..9002375
--- /dev/null
+++ b/test/inputs/missing_options.json
@@ -0,0 +1 @@
+{"version":"0.1","sense":"feas","variables":["x"],"constraints":[["==","x",1],["Int","x"]],"objectives":[]}