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Open-weight model · Text generation

ThinCtx-Qwen3.5-0.8B

by Thinletter thinletter/ThinCtx-Qwen3.5-0.8B

ThinCtx-Qwen3.5-0.8B is an open-weight model for text generation from Thinletter, released under other. It has 752M parameters and a 262,144-token context. At 16-bit it needs about 1.8 GB of GPU memory, which fits on 1x MI300X from $1.85 an hour, at the lowest prices in the SAVRN Index.

ThinCtx by thinletter. ThinCtx-Qwen3.5-0.8B is the ThinCtx conversion of Qwen3.5-0.8B that keeps the GPU memory for the context small: it grows 20 to 30 times more slowly than the base model's cache (0.43 GB instead of 6.0 GB at half a million tokens).

Parameters752M
Context262,144
Weights1.6 GB
Licenseother
AccessOpen weights
Monthly Downloads—

Runs On

What it takes to serve ThinCtx-Qwen3.5-0.8B (752M parameters): the memory its weights need at each precision, and the cheapest way to rent enough data-center GPUs to hold them.

PrecisionWeightsMemory neededCheapest setupPer hourAlso fits
16-bit 1.5 GB 1.8 GB 1x MI300X (192 GB)
Vultr
$1.85 1x H100 $1.99 · 1x MI325X $2.00
8-bit 0.8 GB 0.9 GB 1x MI300X (192 GB)
Vultr
$1.85 1x H100 $1.99 · 1x MI325X $2.00
4-bit 0.4 GB 0.5 GB 1x MI300X (192 GB)
Vultr
$1.85 1x H100 $1.99 · 1x MI325X $2.00

Memory is the weights at that precision plus 20% for the runtime and a short context; a long context needs more. Prices are the lowest on-demand hourly rates in the SAVRN Index, read Oct 16, 2026.

ThinCtx-Qwen3.5-0.8B on every accelerator the SAVRN Index prices, at every precision

Model Card

ThinCtx by thinletter. ThinCtx-Qwen3.5-0.8B is the ThinCtx conversion of Qwen3.5-0.8B that keeps the GPU memory for the context small: it grows 20 to 30 times more slowly than the base model's cache (0.43 GB instead of 6.0 GB at half a million tokens). The part of the context kept on the GPU is small and grows slowly with the length of the conversation or document; the full context is kept in ordinary system memory. ThinCtx trades some speed for this (see Speed below). Chat and tool calling use the Qwen3.5 chat template. Runtime required. ThinCtx models run on the thinctx runtime (pip install thinctx, below). The runtime is what keeps the context memory small; other inference libraries do…

Excerpt from the card by Thinletter, licensed other.

Configuration

Architecture
Qwen3_5ForCausalLM
Context length (tokens)
262,144
Layers
24
Hidden size
1,024
Feed-forward size
3,584
Attention heads
8
Key/value heads
2
Head dimension
256
Vocabulary size
248,320
Model type
qwen3_5_text

Identity and Version

Repository
thinletter/ThinCtx-Qwen3.5-0.8B
Publisher
Thinletter
Task
Text generation
Modality
Text
Library
thinctx
Parameters
752M parameters
Languages
en, cs, de
Revision
ab151e089e8b4a6a84650e76689b5731bfdfc894
First published
2026-10-12
Last updated
2026-10-13

Files and Weights

15 files, 1.6 GB in total. The weights are 2 files totalling 1.6 GB in safetensors.

Weights2 files · 1.6 GB
Configuration3 files · 2.4 KB
Tokenizer2 files · 20.0 MB
Documentation5 files · 22.4 KB
Other2 files · 2.3 MB
Repository1 file · 1.6 KB
Every file
FileTypeSizeSHA-256
aux.safetensorsWeights80.5 MB ad018b8d23ba
model.safetensorsWeights1.5 GB e5ec50b5ad1f
config.jsonConfiguration1.8 KB —
generation_config.jsonConfiguration116 B —
thinctx.jsonConfiguration463 B —
LICENSEDocumentation1.6 KB —
LICENSE-Apache-2.0-Qwen.txtDocumentation8.3 KB —
LICENSE-PolyForm-Small-Business-1.0.0.txtDocumentation4.5 KB —
NOTICEDocumentation793 B —
README.mdDocumentation7.2 KB —
chat_template.jinjaOther7.8 KB —
thinctx_header.pngOther2.3 MB 6b293a9e8411
.gitattributesRepository1.6 KB —
tokenizer.jsonTokenizer20.0 MB a5cd9732badc
tokenizer_config.jsonTokenizer1.5 KB —

License and Download

License
other
Access
Open weights, no gate
Download size
1.6 GB
Download from Thinletter

Released by Thinletter through its official repository on Hugging Face.

Built From

Memory Requirements

PrecisionWeights in memory
As published1.6 GB
16-bit1.5 GB
8-bit0.8 GB
4-bit0.4 GB

Weights only, from the published parameter count; the key-value cache and runtime add to this.

Questions About ThinCtx-Qwen3.5-0.8B

How much GPU memory does ThinCtx-Qwen3.5-0.8B need?

About 1.8 GB at 16-bit and 0.5 GB at 4-bit: the weights (752M parameters) plus a working margin. A long context needs more.

What is the cheapest GPU to run ThinCtx-Qwen3.5-0.8B on?

At 16-bit, 1x MI300X from $1.85 an hour; at 4-bit, 1x MI300X from $1.85 an hour, at the lowest on-demand prices the SAVRN Index lists.

What license is ThinCtx-Qwen3.5-0.8B released under?

other, as its publisher declares it. Read the license text before commercial use.

What is ThinCtx-Qwen3.5-0.8B's context length?

262,144 tokens, from the maximum position embeddings in its published configuration.

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