Step-3.7-Flash is a 198B-parameter sparse Mixture-of-Experts vision-language model from StepFun-ai, activating ~11B parameters per token for up to 400 t/s throughput. It pairs a 196B-parameter language backbone with a 1.8B-parameter vision encoder for native image understanding, supports a 256K context window, and offers three selectable reasoning levels (low / medium / high) to balance speed, cost, and depth. Built for agentic workloads — tool calling, multi-step reasoning, code, and math — with native multilingual coverage.

A separate mmproj projector ships alongside the language quants for multimodal inference. With 128 GB of unified memory (Mac Studio, DGX Spark, Ryzen AI Max+ 395, etc.), you can privately host Step-3.7-Flash: Q4 quants and below run at full 256K context with high precision.

2. Files

File	Quant	Size	Notes
`Step-3.7-flash-BF16.gguf`	BF16	394 GB	Full-precision reference.
`Step-3.7-flash-Q8_0.gguf`	Q8_0	209 GB	Near-lossless. Does not use imatrix.
`Step-3.7-flash-Q4_K_S.gguf`	Q4_K_S	112 GB	imatrix-calibrated. Balanced quality / size.
`Step-3.7-flash-IQ4_XS.gguf`	IQ4_XS	105 GB	imatrix-calibrated. Slightly smaller than Q4_K_S, comparable quality.
`Step-3.7-flash-Q3_K_L.gguf`	Q3_K_L	103 GB	imatrix-calibrated. Aggressive size reduction.
`Step-3.7-flash-Q3_K_M.gguf`	Q3_K_M	94 GB	imatrix-calibrated. Use when you need to fit on a single 64-96 GB device; expect modest quality loss at low bit-widths.
`Step-3.7-flash-IQ3_XXS.gguf`	IQ3_XXS	76 GB	imatrix-calibrated. Recommended only when memory is the primary constraint; offers the smallest footprint among the provided quantizations.
`mmproj-Step-3.7-flash-f16.gguf`	F16	4 GB	Vision projector. Pair with any of the language quants above for image input.

3. Quickstart

Build llama.cpp and run:

bash

# 1. Clone and build
git clone https://github.com/stepfun-ai/llama.cpp.git
cd llama.cpp
git checkout -b step3.7 origin/step3.7
cmake -B build -DLLAMA_BUILD_TOOLS=ON -DLLAMA_BUILD_SERVER=ON
cmake --build build --config Release -j$(nproc)

# 2. Test performance (benchmark)
./build/bin/llama-batched-bench \
  -m Step-3.7-flash-Q4_K_S.gguf \
  -c 32768 -b 2048 -ub 2048 \
  -npp 0,2048,8192,16384,32768 -ntg 128 -npl 1

# 3. Text-only inference
./build/bin/llama-cli \
  -m Step-3.7-flash-Q4_K_S.gguf \
  -c 32768 -ngl 99 -fa on \
  -p "Write a Python function to compute the n-th Fibonacci number."

# 4. With vision (image + text)
./build/bin/llama-mtmd-cli \
  -m Step-3.7-flash-Q4_K_S.gguf \
  --mmproj mmproj-Step-3.7-flash-f16.gguf \
  -c 32768 -ngl 99 -fa on \
  --image path/to/image.jpg \
  -p "Describe this image."

# 5. OpenAI-compatible server (text + vision)
./build/bin/llama-server \
  -m Step-3.7-flash-Q4_K_S.gguf \
  --mmproj mmproj-Step-3.7-flash-f16.gguf \
  -c 32768 -ngl 99 -fa on \
  --host 0.0.0.0 --port 8080

For full CLI / server options, see the llama.cpp README.

4. Performance

Apple Mac Studio (M4 max, 128 GB unified memory)

Step-3.7-flash-Q4_K_S

./llama-batched-bench -m Step-3.7-flash-Q4_K_S.gguf -c 262150 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	PL	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	2.500	51.20	2.500	51.20
2048	128	1	2176	4.873	420.28	2.639	48.51	7.512	289.68
8192	128	1	8320	20.292	403.70	2.757	46.43	23.049	360.97
16384	128	1	16512	42.854	382.32	2.924	43.77	45.779	360.69
32768	128	1	32896	95.168	344.32	3.223	39.72	98.391	334.34
65536	128	1	65664	233.885	280.21	3.909	32.74	237.794	276.14
131072	128	1	131200	635.499	206.25	5.759	22.23	641.258	204.60
262144	128	1	262272	2362.488	110.96	13.188	9.71	2375.677	110.40

Step-3.7-flash-IQ4_XS

./llama-batched-bench -m Step-3.7-flash-IQ4_XS.gguf -c 262150 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	PL	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	2.582	49.58	2.582	49.58
2048	128	1	2176	4.835	423.56	2.679	47.78	7.514	289.60
8192	128	1	8320	19.954	410.55	2.803	45.66	22.757	365.60
16384	128	1	16512	42.142	388.78	2.957	43.29	45.098	366.13
32768	128	1	32896	93.489	350.50	3.288	38.93	96.777	339.91
65536	128	1	65664	227.088	288.59	3.945	32.44	231.033	284.22
131072	128	1	131200	635.047	206.40	5.791	22.10	640.838	204.73
262144	128	1	262272	2170.271	120.79	13.070	9.79	2183.342	120.12

Step-3.7-flash-Q3_K_L

./llama-batched-bench -m Step-3.7-flash-Q3_K_L.gguf -c 262272 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	B	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	3.590	35.66	3.590	35.66
2048	128	1	2176	5.263	389.15	3.702	34.57	8.965	242.72
8192	128	1	8320	21.789	375.97	3.817	33.53	25.606	324.92
16384	128	1	16512	45.819	357.58	3.977	32.18	49.796	331.59
32768	128	1	32896	100.827	324.99	4.308	29.71	105.135	312.89
65536	128	1	65664	242.172	270.62	4.977	25.72	247.149	265.69
131072	128	1	131200	659.645	198.70	6.764	18.92	666.409	196.88
262144	128	1	262272	2200.370	119.14	14.008	9.14	2214.378	118.44

NVIDIA DGX Spark (GB10, 128 GB unified memory)

Step-3.7-flash-Q4_K_S

./llama-batched-bench -m Step-3.7-flash-Q4_K_S.gguf -c 131300 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072 -ntg 128 -npl 1

PP	TG	B	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	5.157	24.82	5.157	24.82
2048	128	1	2176	8.021	255.33	4.907	26.08	12.929	168.31
8192	128	1	8320	10.866	753.89	5.169	24.76	16.035	518.86
16384	128	1	16512	29.389	557.49	6.215	20.60	35.603	463.78
32768	128	1	32896	52.501	624.14	6.931	18.47	59.432	553.50
65536	128	1	65664	112.321	583.47	7.769	16.48	120.090	546.79
131072	128	1	131200	281.479	465.66	9.834	13.02	291.313	450.37

Step-3.7-flash-IQ4_XS

./llama-batched-bench -m Step-3.7-flash-IQ4_XS.gguf -c 262272 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	PL	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	5.368	23.85	5.368	23.85
2048	128	1	2176	4.250	481.87	5.311	24.10	9.561	227.58
8192	128	1	8320	12.531	653.73	5.817	22.01	18.348	453.46
16384	128	1	16512	24.474	669.44	5.915	21.64	30.389	543.35
32768	128	1	32896	51.976	630.44	6.531	19.60	58.508	562.25
65536	128	1	65664	116.305	563.48	7.934	16.13	124.239	528.53
131072	128	1	131200	298.746	438.74	10.263	12.47	309.009	424.58
262144	128	1	262272	924.872	283.44	14.862	8.61	939.734	279.09

Step-3.7-flash-Q3_K_L

./llama-batched-bench -m Step-3.7-flash-Q3_K_L.gguf -c 262272 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	PL	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	5.947	21.52	5.947	21.52
2048	128	1	2176	4.145	494.08	5.623	22.76	9.768	222.77
8192	128	1	8320	14.889	550.20	5.799	22.07	20.688	402.17
16384	128	1	16512	29.374	557.78	6.140	20.85	35.513	464.95
32768	128	1	32896	54.957	596.25	6.744	18.98	61.702	533.15
65536	128	1	65664	129.827	504.79	8.347	15.33	138.174	475.23
131072	128	1	131200	315.402	415.57	10.780	11.87	326.182	402.23
262144	128	1	262272	910.215	288.00	15.568	8.22	925.783	283.30

AMD Ryzen AI Max+ 395 (Strix Halo, 128 GB unified memory)

Step-3.7-flash-Q4_K_S

llama-batched-bench.exe -m Step-3.7-flash-Q4_K_S.gguf -c 65664 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536 -ntg 128 -npl 1

PP	TG	B	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	4.878	26.24	4.878	26.24
2048	128	1	2176	9.367	218.63	5.134	24.93	14.501	150.06
8192	128	1	8320	43.540	188.15	5.508	23.24	49.048	169.63
16384	128	1	16512	111.814	146.53	5.947	21.53	117.761	140.22
32768	128	1	32896	357.819	91.58	6.779	18.88	364.598	90.23
65536	128	1	65664	1342.501	48.82	8.495	15.07	1350.996	48.60

Step-3.7-flash-IQ4_XS

./llama-batched-bench -m Step-3.7-flash-IQ4_XS.gguf -c 65664 -b 2048 -ub 1024 -npp 0,2048,8192,16384,32768,65536 -ntg 128 -npl 1

PP	TG	B	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	5.931	21.58	5.931	21.58
2048	128	1	2176	8.143	251.50	6.194	20.67	14.337	151.78
8192	128	1	8320	39.899	205.32	6.521	19.63	46.420	179.23
16384	128	1	16512	105.098	155.89	6.891	18.57	111.989	147.44
32768	128	1	32896	338.645	96.76	7.793	16.42	346.439	94.95
65536	128	1	65664	1310.820	50.00	9.489	13.49	1320.309	49.73

Step-3.7-flash-Q3_K_L

./llama-batched-bench -m Step-3.7-flash-Q3_K_L.gguf -c 262272 -b 2048 -ub 1024 -ctk q8_0 -ctv q8_0 -npp 0,2048,8192,16384,32768,65536,131072,262144 -ntg 128 -npl 1

PP	TG	B	N_KV	T_PP s	S_PP t/s	T_TG s	S_TG t/s	T s	S t/s
0	128	1	128	0.000	0.00	5.015	25.53	5.015	25.53
2048	128	1	2176	10.246	199.88	5.073	25.23	15.319	142.04
8192	128	1	8320	37.229	220.05	5.341	23.96	42.570	195.44
16384	128	1	16512	79.234	206.78	5.489	23.32	84.723	194.89
32768	128	1	32896	179.697	182.35	5.810	22.03	185.507	177.33
65536	128	1	65664	436.593	150.11	6.577	19.46	443.169	148.17
131072	128	1	131200	1262.377	103.83	9.124	14.03	1271.501	103.19
262144	128	1	262272	3487.921	75.16	11.391	11.24	3499.312	74.95

5. Acknowledgments

This release stands on the work of the following authors and communities:

bartowski — for calibration_datav5, the community-standard imatrix calibration anchor used by countless GGUF releases. Used for calibration purposes only; no license has been verified for this resource.
eaddario — for the imatrix-calibration dataset (MIT), providing multilingual / code / math splits that form the backbone of this release's domain balance
NousResearch — for hermes-function-calling-v1 (Apache-2.0), used for agent / tool-call calibration coverage
ggml-org / llama.cpp — for the entire quantization and inference toolchain (MIT)

6. License

The GGUF quantization files in this repository are derivative works of stepfun-ai/Step-3.7-Flash and are released under the same Apache 2.0 license.

Component	License
Base model weights (stepfun-ai/Step-3.7-Flash)	Apache-2.0
Calibration dataset (eaddario/imatrix-calibration)	MIT
Calibration dataset (NousResearch/hermes-function-calling-v1)	Apache-2.0
Quantization toolchain (llama.cpp)	MIT

All calibration datasets retain their original licenses and are used strictly for quantization calibration purposes only.

stepfun-ai/Step-3.7-Flash-GGUF

1. Introduction

2. Files

3. Quickstart

4. Performance

Apple Mac Studio (M4 max, 128 GB unified memory)

NVIDIA DGX Spark (GB10, 128 GB unified memory)

AMD Ryzen AI Max+ 395 (Strix Halo, 128 GB unified memory)

5. Acknowledgments

6. License

stepfun-ai/
Step-3.7-Flash-GGUF